diff --git a/client/settings/connect-stripe-account/__tests__/connect-stripe-account.test.js b/client/settings/connect-stripe-account/__tests__/connect-stripe-account.test.js
index ab4d5ce48..38d1f406e 100644
--- a/client/settings/connect-stripe-account/__tests__/connect-stripe-account.test.js
+++ b/client/settings/connect-stripe-account/__tests__/connect-stripe-account.test.js
@@ -26,7 +26,26 @@ describe( 'ConnectStripeAccount', () => {
 		).toBeInTheDocument();
 	} );
 
-	it( 'should render both the Connect Account and Enter keys buttons when the Stripe OAuth link is provided', () => {
+	it( 'should render both the "Create or connect an account" and "Create or connect a test account" buttons when both Stripe OAuth links are provided', () => {
+		render(
+			<ConnectStripeAccount
+				oauthUrl="https://connect.stripe.com/oauth/v2/authorize?response_type=code&client_id=ca_1234&scope=read_write&state=1234"
+				testOauthUrl="https://connect.stripe.com/oauth/v2/authorize?response_type=code&client_id=ca_5678&scope=read_write&state=5678"
+			/>
+		);
+
+		expect( screen.queryByText( 'Terms of service.' ) ).toBeInTheDocument();
+
+		expect(
+			screen.getByText( 'Create or connect an account' )
+		).toBeInTheDocument();
+
+		expect(
+			screen.getByText( 'Create or connect a test account instead' )
+		).toBeInTheDocument();
+	} );
+
+	it( 'should render only the "Create or connect an account" button when only the Stripe OAuth link is provided', () => {
 		render(
 			<ConnectStripeAccount oauthUrl="https://connect.stripe.com/oauth/v2/authorize?response_type=code&client_id=ca_1234&scope=read_write&state=1234" />
 		);
@@ -38,7 +57,32 @@ describe( 'ConnectStripeAccount', () => {
 		).toBeInTheDocument();
 
 		expect(
-			screen.queryByText( 'Enter account keys (advanced)' )
+			screen.queryByText( 'Create or connect a test account' )
+		).not.toBeInTheDocument();
+
+		expect(
+			screen.queryByText( 'Create or connect a test account instead' )
+		).not.toBeInTheDocument();
+	} );
+
+	it( 'should render only the "Create or connect a test account" button when only the Stripe Test OAuth link is provided', () => {
+		render(
+			<ConnectStripeAccount testOauthUrl="https://connect.stripe.com/oauth/v2/authorize?response_type=code&client_id=ca_5678&scope=read_write&state=5678" />
+		);
+
+		expect( screen.queryByText( 'Terms of service.' ) ).toBeInTheDocument();
+
+		expect(
+			screen.getByText( 'Create or connect a test account' )
+		).toBeInTheDocument();
+
+		// It should not have the "instead" word at the end
+		expect(
+			screen.queryByText( 'Create or connect a test account instead' )
+		).not.toBeInTheDocument();
+
+		expect(
+			screen.queryByText( 'Create or connect an account' )
 		).not.toBeInTheDocument();
 	} );
 
@@ -60,6 +104,11 @@ describe( 'ConnectStripeAccount', () => {
 		);
 		userEvent.click( connectAccountButton );
 
+		expect( recordEvent ).toHaveBeenCalledWith(
+			'wcstripe_create_or_connect_account_click',
+			{}
+		);
+
 		expect( window.location.assign ).toHaveBeenCalledWith( oauthUrl );
 
 		// Set the original function back to keep further tests working as expected.
@@ -68,19 +117,42 @@ describe( 'ConnectStripeAccount', () => {
 		} );
 	} );
 
-	it( 'should record a "wcstripe_create_or_connect_account_click" Track event when clicking on the Connect account button', () => {
+	it( 'should redirect to the Stripe Test OAuth link when clicking on the "Create or connect a test account" button', () => {
+		// Keep the original function at hand.
+		const assign = window.location.assign;
+
+		Object.defineProperty( window, 'location', {
+			value: { assign: jest.fn() },
+		} );
+
+		const oauthUrl =
+			'https://connect.stripe.com/oauth/v2/authorize?response_type=code&client_id=ca_1234&scope=read_write&state=1234';
+
+		const testOauthUrl =
+			'https://connect.stripe.com/oauth/v2/authorize?response_type=code&client_id=ca_5678&scope=read_write&state=5678';
+
 		render(
-			<ConnectStripeAccount oauthUrl="https://connect.stripe.com/oauth/v2/authorize?response_type=code&client_id=ca_1234&scope=read_write&state=1234" />
+			<ConnectStripeAccount
+				oauthUrl={ oauthUrl }
+				testOauthUrl={ testOauthUrl }
+			/>
 		);
 
-		const connectAccountButton = screen.getByText(
-			'Create or connect an account'
+		const connectTestAccountButton = screen.getByText(
+			'Create or connect a test account instead'
 		);
-		userEvent.click( connectAccountButton );
+		userEvent.click( connectTestAccountButton );
 
 		expect( recordEvent ).toHaveBeenCalledWith(
-			'wcstripe_create_or_connect_account_click',
+			'wcstripe_create_or_connect_test_account_click',
 			{}
 		);
+
+		expect( window.location.assign ).toHaveBeenCalledWith( testOauthUrl );
+
+		// Set the original function back to keep further tests working as expected.
+		Object.defineProperty( window, 'location', {
+			value: { assign },
+		} );
 	} );
 } );
diff --git a/client/settings/connect-stripe-account/index.js b/client/settings/connect-stripe-account/index.js
index 97b10cf6f..c2f21bbb5 100644
--- a/client/settings/connect-stripe-account/index.js
+++ b/client/settings/connect-stripe-account/index.js
@@ -47,12 +47,17 @@ const ButtonWrapper = styled.div`
 	}
 `;
 
-const ConnectStripeAccount = ( { oauthUrl } ) => {
+const ConnectStripeAccount = ( { oauthUrl, testOauthUrl } ) => {
 	const handleCreateOrConnectAccount = () => {
 		recordEvent( 'wcstripe_create_or_connect_account_click', {} );
 		window.location.assign( oauthUrl );
 	};
 
+	const handleCreateOrConnectTestAccount = () => {
+		recordEvent( 'wcstripe_create_or_connect_test_account_click', {} );
+		window.location.assign( testOauthUrl );
+	};
+
 	return (
 		<CardWrapper>
 			<StripeBanner />
@@ -70,38 +75,58 @@ const ConnectStripeAccount = ( { oauthUrl } ) => {
 					) }
 				</InformationText>
 
-				{ oauthUrl && (
-					<TermsOfServiceText>
-						{ interpolateComponents( {
-							mixedString: __(
-								'By clicking "Create or connect an account", you agree to the {{tosLink}}Terms of service.{{/tosLink}}',
-								'woocommerce-gateway-stripe'
-							),
-							components: {
-								tosLink: (
-									// eslint-disable-next-line jsx-a11y/anchor-has-content
-									<a
-										target="_blank"
-										rel="noreferrer"
-										href="https://wordpress.com/tos"
-									/>
+				{ oauthUrl || testOauthUrl ? (
+					<>
+						<TermsOfServiceText>
+							{ interpolateComponents( {
+								mixedString: __(
+									'By clicking "Create or connect an account", you agree to the {{tosLink}}Terms of service.{{/tosLink}}',
+									'woocommerce-gateway-stripe'
 								),
-							},
-						} ) }
-					</TermsOfServiceText>
-				) }
-				{ oauthUrl ? (
-					<ButtonWrapper>
-						<Button
-							variant="primary"
-							onClick={ handleCreateOrConnectAccount }
-						>
-							{ __(
-								'Create or connect an account',
-								'woocommerce-gateway-stripe'
+								components: {
+									tosLink: (
+										// eslint-disable-next-line jsx-a11y/anchor-has-content
+										<a
+											target="_blank"
+											rel="noreferrer"
+											href="https://wordpress.com/tos"
+										/>
+									),
+								},
+							} ) }
+						</TermsOfServiceText>
+						<ButtonWrapper>
+							{ oauthUrl && (
+								<Button
+									variant="primary"
+									onClick={ handleCreateOrConnectAccount }
+								>
+									{ __(
+										'Create or connect an account',
+										'woocommerce-gateway-stripe'
+									) }
+								</Button>
+							) }
+							{ testOauthUrl && (
+								<Button
+									variant={
+										oauthUrl ? 'secondary' : 'primary'
+									}
+									onClick={ handleCreateOrConnectTestAccount }
+								>
+									{ oauthUrl
+										? __(
+												'Create or connect a test account instead',
+												'woocommerce-gateway-stripe'
+										  )
+										: __(
+												'Create or connect a test account',
+												'woocommerce-gateway-stripe'
+										  ) }
+								</Button>
 							) }
-						</Button>
-					</ButtonWrapper>
+						</ButtonWrapper>
+					</>
 				) : (
 					<InlineNotice isDismissible={ false } status="error">
 						{ interpolateComponents( {
diff --git a/client/settings/index.js b/client/settings/index.js
index ca60a5dec..ae7b15f56 100644
--- a/client/settings/index.js
+++ b/client/settings/index.js
@@ -49,6 +49,7 @@ if ( newAccountContainer ) {
 	ReactDOM.render(
 		<ConnectStripeAccount
 			oauthUrl={ wc_stripe_settings_params.stripe_oauth_url }
+			testOauthUrl={ wc_stripe_settings_params.stripe_test_oauth_url }
 		/>,
 		newAccountContainer
 	);
diff --git a/client/settings/stripe-auth-account/stripe-auth-actions.js b/client/settings/stripe-auth-account/stripe-auth-actions.js
index ccce29a67..86859315e 100644
--- a/client/settings/stripe-auth-account/stripe-auth-actions.js
+++ b/client/settings/stripe-auth-account/stripe-auth-actions.js
@@ -1,4 +1,5 @@
 /* global wc_stripe_settings_params */
+import { __ } from '@wordpress/i18n';
 import { React } from 'react';
 import { Button } from '@wordpress/components';
 import ConfigureWebhookButton from './configure-webhook-button';
@@ -17,9 +18,21 @@ const StripeAuthActions = ( { testMode, displayWebhookConfigure } ) => {
 		<div className="woocommerce-stripe-auth__actions">
 			<Button
 				variant="primary"
-				href={ wc_stripe_settings_params.stripe_oauth_url }
+				href={
+					testMode
+						? wc_stripe_settings_params.stripe_test_oauth_url
+						: wc_stripe_settings_params.stripe_oauth_url
+				}
 				text={
-					testMode ? 'Connect a test account' : 'Connect an account'
+					testMode
+						? __(
+								'Create or connect a test account',
+								'woocommerce-gateway-stripe'
+						  )
+						: __(
+								'Create or connect an account',
+								'woocommerce-gateway-stripe'
+						  )
 				}
 			/>
 			{ displayWebhookConfigure && (
diff --git a/includes/admin/class-wc-stripe-settings-controller.php b/includes/admin/class-wc-stripe-settings-controller.php
index 90d94bb9c..fae5010d1 100644
--- a/includes/admin/class-wc-stripe-settings-controller.php
+++ b/includes/admin/class-wc-stripe-settings-controller.php
@@ -130,9 +130,10 @@ public function admin_scripts( $hook_suffix ) {
 		);
 
 		$oauth_url = woocommerce_gateway_stripe()->connect->get_oauth_url();
-		if ( is_wp_error( $oauth_url ) ) {
-			$oauth_url = '';
-		}
+		$oauth_url = is_wp_error( $oauth_url ) ? '' : $oauth_url;
+
+		$test_oauth_url = woocommerce_gateway_stripe()->connect->get_oauth_url( '', 'test' );
+		$test_oauth_url = is_wp_error( $test_oauth_url ) ? '' : $test_oauth_url;
 
 		$message = sprintf(
 		/* translators: 1) Html strong opening tag 2) Html strong closing tag */
@@ -146,6 +147,7 @@ public function admin_scripts( $hook_suffix ) {
 			'i18n_out_of_sync'          => $message,
 			'is_upe_checkout_enabled'   => WC_Stripe_Feature_Flags::is_upe_checkout_enabled(),
 			'stripe_oauth_url'          => $oauth_url,
+			'stripe_test_oauth_url'     => $test_oauth_url,
 			'show_customization_notice' => get_option( 'wc_stripe_show_customization_notice', 'yes' ) === 'yes' ? true : false,
 			'is_test_mode'              => $this->gateway->is_in_test_mode(),
 			'plugin_version'            => WC_STRIPE_VERSION,
diff --git a/includes/class-wc-gateway-stripe.php b/includes/class-wc-gateway-stripe.php
index adad5e5f7..3381ca53e 100644
--- a/includes/class-wc-gateway-stripe.php
+++ b/includes/class-wc-gateway-stripe.php
@@ -1122,20 +1122,6 @@ public function get_required_settings_keys() {
 		return [ 'publishable_key', 'secret_key' ];
 	}
 
-	/**
-	 * Get the connection URL.
-	 *
-	 * @return string Connection URL.
-	 */
-	public function get_connection_url( $return_url = '' ) {
-		$api     = new WC_Stripe_Connect_API();
-		$connect = new WC_Stripe_Connect( $api );
-
-		$url = $connect->get_oauth_url( $return_url );
-
-		return is_wp_error( $url ) ? null : $url;
-	}
-
 	/**
 	 * Get help text to display during quick setup.
 	 *
diff --git a/includes/class-wc-stripe-account.php b/includes/class-wc-stripe-account.php
index 8b2c17c17..3b972d681 100644
--- a/includes/class-wc-stripe-account.php
+++ b/includes/class-wc-stripe-account.php
@@ -46,42 +46,52 @@ public function __construct( WC_Stripe_Connect $connect, $stripe_api ) {
 	/**
 	 * Gets and caches the data for the account connected to this site.
 	 *
+	 * @param string|null $mode Optional. The mode to get the account data for. 'live' or 'test'. Default will use the current mode.
 	 * @return array Account data or empty if failed to retrieve account data.
 	 */
-	public function get_cached_account_data() {
-		if ( ! $this->connect->is_connected() ) {
+	public function get_cached_account_data( $mode = null ) {
+		if ( ! $this->connect->is_connected( $mode ) ) {
 			return [];
 		}
 
-		$account = $this->read_account_from_cache();
+		$account = $this->read_account_from_cache( $mode );
 
 		if ( ! empty( $account ) ) {
 			return $account;
 		}
 
-		return $this->cache_account();
+		return $this->cache_account( $mode );
 	}
 
 	/**
 	 * Read the account from the WP option we cache it in.
 	 *
+	 * @param string|null $mode Optional. The mode to get the account data for. 'live' or 'test'. Default will use the current mode.
 	 * @return array empty when no data found in transient, otherwise returns cached data
 	 */
-	private function read_account_from_cache() {
-		$account_cache = json_decode( wp_json_encode( get_transient( $this->get_transient_key() ) ), true );
+	private function read_account_from_cache( $mode = null ) {
+		$account_cache = json_decode( wp_json_encode( get_transient( $this->get_transient_key( $mode ) ) ), true );
 
 		return false === $account_cache ? [] : $account_cache;
 	}
 
 	/**
 	 * Caches account data for a period of time.
+	 *
+	 * @param string|null $mode Optional. The mode to get the account data for. 'live' or 'test'. Default will use the current mode.
 	 */
-	private function cache_account() {
-		$expiration = 2 * HOUR_IN_SECONDS;
+	private function cache_account( $mode = null ) {
+		// If a mode is provided, we'll set the API secret key to the appropriate key to retrieve the account data.
+		if ( ! is_null( $mode ) ) {
+			WC_Stripe_API::set_secret_key_for_mode( $mode );
+		}
 
-		// need call_user_func() as (  $this->stripe_api )::retrieve this syntax is not supported in php < 5.2
+		// need call_user_func() as ( $this->stripe_api )::retrieve this syntax is not supported in php < 5.2
 		$account = call_user_func( [ $this->stripe_api, 'retrieve' ], 'account' );
 
+		// Restore the secret key to the original value.
+		WC_Stripe_API::set_secret_key_for_mode();
+
 		if ( is_wp_error( $account ) || isset( $account->error->message ) ) {
 			return [];
 		}
@@ -90,21 +100,27 @@ private function cache_account() {
 		$account_cache = $account;
 
 		// Create or update the account option cache.
-		set_transient( $this->get_transient_key(), $account_cache, $expiration );
+		set_transient( $this->get_transient_key( $mode ), $account_cache, 2 * HOUR_IN_SECONDS );
 
 		return json_decode( wp_json_encode( $account ), true );
 	}
 
 	/**
-	 * Checks Stripe connection mode if it is test mode or live mode
+	 * Fetches the transient key for the account data for a given mode.
+	 * If no mode is provided, it will use the current mode.
 	 *
+	 * @param string|null $mode Optional. The mode to get the account data for. 'live' or 'test'. Default will use the current mode.
 	 * @return string Transient key of test mode when testmode is enabled, otherwise returns the key of live mode.
 	 */
-	private function get_transient_key() {
+	private function get_transient_key( $mode = null ) {
 		$settings_options = get_option( 'woocommerce_stripe_settings', [] );
-		$key              = isset( $settings_options['testmode'] ) && 'yes' === $settings_options['testmode'] ? self::TEST_ACCOUNT_OPTION : self::LIVE_ACCOUNT_OPTION;
 
-		return $key;
+		// If the mode is not provided or is invalid, we'll check the current mode.
+		if ( is_null( $mode ) || ! in_array( $mode, [ 'test', 'live' ] ) ) {
+			$mode = isset( $settings_options['testmode'] ) && 'yes' === $settings_options['testmode'] ? 'test' : 'live';
+		}
+
+		return 'test' === $mode ? self::TEST_ACCOUNT_OPTION : self::LIVE_ACCOUNT_OPTION;
 	}
 
 	/**
diff --git a/includes/class-wc-stripe-api.php b/includes/class-wc-stripe-api.php
index 4f0141538..46aadf7f8 100644
--- a/includes/class-wc-stripe-api.php
+++ b/includes/class-wc-stripe-api.php
@@ -39,17 +39,28 @@ public static function set_secret_key( $secret_key ) {
 	 */
 	public static function get_secret_key() {
 		if ( ! self::$secret_key ) {
-			$options         = get_option( 'woocommerce_stripe_settings' );
-			$secret_key      = $options['secret_key'] ?? '';
-			$test_secret_key = $options['test_secret_key'] ?? '';
-
-			if ( isset( $options['testmode'] ) ) {
-				self::set_secret_key( 'yes' === $options['testmode'] ? $test_secret_key : $secret_key );
-			}
+			self::set_secret_key_for_mode();
 		}
 		return self::$secret_key;
 	}
 
+	/**
+	 * Set secret key based on mode.
+	 *
+	 * @param string|null $mode Optional. The mode to set the secret key for. 'live' or 'test'. Default will set the secret for the currently active mode.
+	 */
+	public static function set_secret_key_for_mode( $mode = null ) {
+		$options         = get_option( 'woocommerce_stripe_settings' );
+		$secret_key      = $options['secret_key'] ?? '';
+		$test_secret_key = $options['test_secret_key'] ?? '';
+
+		if ( is_null( $mode ) || ! in_array( $mode, [ 'test', 'live' ] ) ) {
+			$mode = isset( $options['testmode'] ) && 'yes' === $options['testmode'] ? 'test' : 'live';
+		}
+
+		self::set_secret_key( 'test' === $mode ? $test_secret_key : $secret_key );
+	}
+
 	/**
 	 * Generates the user agent we use to pass to API request so
 	 * Stripe can identify our application.
diff --git a/includes/connect/class-wc-stripe-connect-api.php b/includes/connect/class-wc-stripe-connect-api.php
index 374f568f4..1e5720f54 100644
--- a/includes/connect/class-wc-stripe-connect-api.php
+++ b/includes/connect/class-wc-stripe-connect-api.php
@@ -18,13 +18,14 @@ class WC_Stripe_Connect_API {
 		/**
 		 * Send request to Connect Server to initiate Stripe OAuth
 		 *
-		 * @param  string $return_url return address.
+		 * @param string $return_url The URL to return to after the OAuth is completed.
+		 * @param string $mode       Optional. The mode to connect to. 'live' or 'test'. Default is 'live'.
 		 *
-		 * @return array
+		 * @return array|WP_Error The response from the server.
 		 */
-		public function get_stripe_oauth_init( $return_url ) {
-
+		public function get_stripe_oauth_init( $return_url, $mode = 'live' ) {
 			$current_user                   = wp_get_current_user();
+			$account                        = WC_Stripe::get_instance()->account->get_cached_account_data( $mode );
 			$business_data                  = [];
 			$business_data['url']           = get_site_url();
 			$business_data['business_name'] = html_entity_decode( get_bloginfo( 'name' ), ENT_QUOTES );
@@ -55,21 +56,30 @@ public function get_stripe_oauth_init( $return_url ) {
 				'businessData' => $business_data,
 			];
 
-			return $this->request( 'POST', '/stripe/oauth-init', $request );
+			// If the store is already connected to an account and the account is connected to an Application, send the account ID so
+			// api.woocommerce.com can determine the type of connection needed.
+			if ( isset( $account['id'], $account['controller']['type'] ) && 'application' === $account['controller']['type'] ) {
+				$request['accountId'] = $account['id'];
+			}
+
+			$path = 'test' === $mode ? '/stripe-sandbox/oauth-init' : '/stripe/oauth-init';
+
+			return $this->request( 'POST', $path, $request );
 		}
 
 		/**
 		 * Send request to Connect Server for Stripe keys
 		 *
-		 * @param  string $code OAuth server code.
+		 * @param string $code OAuth server code.
+		 * @param string $mode Optional. The mode to connect to. 'live' or 'test'. Default is 'live'.
 		 *
 		 * @return array
 		 */
-		public function get_stripe_oauth_keys( $code ) {
-
+		public function get_stripe_oauth_keys( $code, $mode = 'live' ) {
 			$request = [ 'code' => $code ];
 
-			return $this->request( 'POST', '/stripe/oauth-keys', $request );
+			$path = 'test' === $mode ? '/stripe-sandbox/oauth-keys' : '/stripe/oauth-keys';
+			return $this->request( 'POST', $path, $request );
 		}
 
 		/**
diff --git a/includes/connect/class-wc-stripe-connect.php b/includes/connect/class-wc-stripe-connect.php
index 7a65aa65b..32aa0a859 100644
--- a/includes/connect/class-wc-stripe-connect.php
+++ b/includes/connect/class-wc-stripe-connect.php
@@ -33,11 +33,12 @@ public function __construct( WC_Stripe_Connect_API $api ) {
 		/**
 		 * Gets the OAuth URL for Stripe onboarding flow
 		 *
-		 * @param  string $return_url url to return to after oauth flow.
+		 * @param string $return_url The URL to return to after OAuth flow.
+		 * @param string $mode       Optional. The mode to connect to. 'live' or 'test'. Default is 'live'.
 		 *
 		 * @return string|WP_Error
 		 */
-		public function get_oauth_url( $return_url = '' ) {
+		public function get_oauth_url( $return_url = '', $mode = 'live' ) {
 
 			if ( empty( $return_url ) ) {
 				$return_url = admin_url( 'admin.php?page=wc-settings&tab=checkout&section=stripe&panel=settings' );
@@ -49,7 +50,7 @@ public function get_oauth_url( $return_url = '' ) {
 
 			$return_url = add_query_arg( '_wpnonce', wp_create_nonce( 'wcs_stripe_connected' ), $return_url );
 
-			$result = $this->api->get_stripe_oauth_init( $return_url );
+			$result = $this->api->get_stripe_oauth_init( $return_url, $mode );
 
 			if ( is_wp_error( $result ) ) {
 				return $result;
@@ -63,12 +64,13 @@ public function get_oauth_url( $return_url = '' ) {
 		/**
 		 * Initiate OAuth connection request to Connect Server
 		 *
-		 * @param  string $state State token to prevent request forgery.
-		 * @param  string $code  OAuth code.
+		 * @param string $state State token to prevent request forgery.
+		 * @param string $code  OAuth code.
+		 * @param string $mode  Optional. The mode to connect to. 'live' or 'test'. Default is 'live'.
 		 *
 		 * @return string|WP_Error
 		 */
-		public function connect_oauth( $state, $code ) {
+		public function connect_oauth( $state, $code, $mode = 'live' ) {
 			// The state parameter is used to protect against CSRF.
 			// It's a unique, randomly generated, opaque, and non-guessable string that is sent when starting the
 			// authentication request and validated when processing the response.
@@ -76,7 +78,7 @@ public function connect_oauth( $state, $code ) {
 				return new WP_Error( 'Invalid state received from Stripe server' );
 			}
 
-			$response = $this->api->get_stripe_oauth_keys( $code );
+			$response = $this->api->get_stripe_oauth_keys( $code, $mode );
 
 			if ( is_wp_error( $response ) ) {
 				return $response;
@@ -84,7 +86,7 @@ public function connect_oauth( $state, $code ) {
 
 			delete_transient( 'wcs_stripe_connect_state' );
 
-			return $this->save_stripe_keys( $response );
+			return $this->save_stripe_keys( $response, $mode );
 		}
 
 		/**
@@ -107,11 +109,15 @@ public function maybe_handle_redirect() {
 					return new WP_Error( 'Invalid nonce received from Stripe server' );
 				}
 
-				$response = $this->connect_oauth( wc_clean( wp_unslash( $_GET['wcs_stripe_state'] ) ), wc_clean( wp_unslash( $_GET['wcs_stripe_code'] ) ) );
+				$state = wc_clean( wp_unslash( $_GET['wcs_stripe_state'] ) );
+				$code  = wc_clean( wp_unslash( $_GET['wcs_stripe_code'] ) );
+				$mode  = isset( $_GET['wcs_stripe_mode'] ) ? wc_clean( wp_unslash( $_GET['wcs_stripe_mode'] ) ) : 'live';
+
+				$response = $this->connect_oauth( $state, $code, $mode );
 
 				$this->record_account_connect_track_event( is_wp_error( $response ) );
 
-				wp_safe_redirect( esc_url_raw( remove_query_arg( [ 'wcs_stripe_state', 'wcs_stripe_code' ] ) ) );
+				wp_safe_redirect( esc_url_raw( remove_query_arg( [ 'wcs_stripe_state', 'wcs_stripe_code', 'wcs_stripe_mode' ] ) ) );
 				exit;
 			}
 		}
@@ -119,17 +125,18 @@ public function maybe_handle_redirect() {
 		/**
 		 * Saves stripe keys after OAuth response
 		 *
-		 * @param  array $result OAuth response result.
+		 * @param array $result OAuth response result.
+		 * @param string $mode Optional. The mode to connect to. 'live' or 'test'. Default is 'live'.
 		 *
 		 * @return array|WP_Error
 		 */
-		private function save_stripe_keys( $result ) {
+		private function save_stripe_keys( $result, $mode = 'live' ) {
 
 			if ( ! isset( $result->publishableKey, $result->secretKey ) ) { // phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase
 				return new WP_Error( 'Invalid credentials received from WooCommerce Connect server' );
 			}
 
-			$is_test                                    = false !== strpos( $result->publishableKey, '_test_' ); // phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase
+			$is_test                                    = 'live' !== $mode;
 			$prefix                                     = $is_test ? 'test_' : '';
 			$default_options                            = $this->get_default_stripe_config();
 			$options                                    = array_merge( $default_options, get_option( self::SETTINGS_OPTION, [] ) );
diff --git a/tests/phpunit/test-class-wc-stripe-account.php b/tests/phpunit/test-class-wc-stripe-account.php
index 0f0579424..1fd4b6e5e 100644
--- a/tests/phpunit/test-class-wc-stripe-account.php
+++ b/tests/phpunit/test-class-wc-stripe-account.php
@@ -192,4 +192,72 @@ public function test_get_account_country() {
 		set_transient( 'wcstripe_account_data_test', $account );
 		$this->assertEquals( 'US', $this->account->get_account_country() );
 	}
+
+	/**
+	 * Test for get_cached_account_data() with test mode parameter.
+	 */
+	public function test_get_cached_account_data_test_mode() {
+		$this->mock_connect->method( 'is_connected' )->with( 'test' )->willReturn( true );
+
+		// Test mode account data.
+		$account = [
+			'id'      => 'acct_1234',
+			'email'   => 'test@example.com',
+			'country' => 'US',
+		];
+		set_transient( 'wcstripe_account_data_test', $account );
+
+		$this->assertSame( $this->account->get_cached_account_data( 'test' ), $account );
+	}
+
+	/**
+	 * Test for get_cached_account_data() with live mode parameter.
+	 */
+	public function test_get_cached_account_data_live_mode() {
+		$this->mock_connect->method( 'is_connected' )->with( 'live' )->willReturn( true );
+
+		// Live mode account data.
+		$account = [
+			'id'      => 'acct_1234',
+			'email'   => 'live@example.com',
+			'country' => 'US',
+		];
+		set_transient( 'wcstripe_account_data_live', $account );
+
+		$this->assertSame( $this->account->get_cached_account_data( 'live' ), $account );
+	}
+
+	/**
+	 * Test for get_cached_account_data() with no mode parameter.
+	 */
+	public function test_get_cached_account_data_no_mode() {
+		$stripe_settings = get_option( 'woocommerce_stripe_settings' );
+		$this->mock_connect->method( 'is_connected' )->with( null )->willReturn( true );
+
+		$test_account = [
+			'id'      => 'acct_test-1234',
+			'email'   => 'john@example.com',
+		];
+
+		$live_account = [
+			'id'      => 'acct_live-1234',
+			'email'   => 'john@example.com',
+		];
+		set_transient( 'wcstripe_account_data_test', $test_account );
+		set_transient( 'wcstripe_account_data_live', $live_account );
+
+		// Enable TEST mode.
+		$stripe_settings['testmode'] = 'yes';
+		update_option( 'woocommerce_stripe_settings', $stripe_settings );
+
+		// Confirm test mode data is returned.
+		$this->assertSame( $this->account->get_cached_account_data(), $test_account );
+
+		// Enable LIVE mode.
+		$stripe_settings['testmode'] = 'no';
+		update_option( 'woocommerce_stripe_settings', $stripe_settings );
+
+		// Confirm live mode data is returned.
+		$this->assertSame( $this->account->get_cached_account_data(), $live_account );
+	}
 }
diff --git a/tests/phpunit/test-class-wc-stripe-api.php b/tests/phpunit/test-class-wc-stripe-api.php
new file mode 100644
index 000000000..2878a1e84
--- /dev/null
+++ b/tests/phpunit/test-class-wc-stripe-api.php
@@ -0,0 +1,97 @@
+<?php
+/**
+ * Class WC_Stripe_API
+ *
+ * @package WooCommerce_Stripe/Tests/WC_Stripe_API
+ */
+
+/**
+ * Class WC_Stripe_API tests.
+ */
+class WC_Stripe_API_Test extends WP_UnitTestCase {
+
+	/**
+	 * Secret key for test mode.
+	 */
+	const TEST_SECRET_KEY = 'sk_test_key_123';
+
+	/**
+	 * Secret key for live mode.
+	 */
+	const LIVE_SECRET_KEY = 'sk_live_key_123';
+
+	/**
+	 * Setup environment for tests.
+	 */
+	public function set_up() {
+		parent::set_up();
+
+		$stripe_settings                         = get_option( 'woocommerce_stripe_settings' );
+		$stripe_settings['enabled']              = 'yes';
+		$stripe_settings['testmode']             = 'yes';
+		$stripe_settings['secret_key']           = self::LIVE_SECRET_KEY;
+		$stripe_settings['test_secret_key']      = self::TEST_SECRET_KEY;
+		update_option( 'woocommerce_stripe_settings', $stripe_settings );
+	}
+
+	/**
+	 * Tear down environment after tests.
+	 */
+	public function tear_down() {
+		delete_option( 'woocommerce_stripe_settings' );
+		WC_Stripe_API::set_secret_key( null );
+		parent::tear_down();
+	}
+
+	/**
+	 * Test get_secret_key and set_secret_key.
+	 */
+	public function test_set_secret_key() {
+		$secret_key = 'sk_test_key';
+		WC_Stripe_API::set_secret_key( $secret_key );
+
+		$this->assertEquals( $secret_key, WC_Stripe_API::get_secret_key() );
+	}
+
+	/**
+	 * Test WC_Stripe_API::set_secret_key_for_mode() with no parameter.
+	 */
+	public function test_set_secret_key_for_mode_no_parameter() {
+		// Base test - current mode is test.
+		WC_Stripe_API::set_secret_key_for_mode();
+
+		$this->assertEquals( self::TEST_SECRET_KEY, WC_Stripe_API::get_secret_key() );
+
+		// Enable live mode.
+		$stripe_settings = get_option( 'woocommerce_stripe_settings' );
+		$stripe_settings['testmode'] = 'no';
+		update_option( 'woocommerce_stripe_settings', $stripe_settings );
+
+		WC_Stripe_API::set_secret_key_for_mode();
+
+		$this->assertEquals( self::LIVE_SECRET_KEY, WC_Stripe_API::get_secret_key() );
+	}
+
+	/**
+	 * Test WC_Stripe_API::set_secret_key_for_mode() with mode parameters.
+	 */
+	public function test_set_secret_key_for_mode_with_parameter() {
+		WC_Stripe_API::set_secret_key_for_mode( 'test' );
+		$this->assertEquals( self::TEST_SECRET_KEY, WC_Stripe_API::get_secret_key() );
+
+		WC_Stripe_API::set_secret_key_for_mode( 'live' );
+		$this->assertEquals( self::LIVE_SECRET_KEY, WC_Stripe_API::get_secret_key() );
+
+		// Invalid parameters will set the secret key to the current mode.
+		WC_Stripe_API::set_secret_key_for_mode( 'invalid' );
+		$this->assertEquals( self::TEST_SECRET_KEY, WC_Stripe_API::get_secret_key() );
+
+		// Set the mode to live and test the invalid parameter.
+		$stripe_settings = get_option( 'woocommerce_stripe_settings' );
+		$stripe_settings['testmode'] = 'no';
+		update_option( 'woocommerce_stripe_settings', $stripe_settings );
+
+		WC_Stripe_API::set_secret_key_for_mode( 'invalid' );
+		$this->assertEquals( self::LIVE_SECRET_KEY, WC_Stripe_API::get_secret_key() );
+	}
+}