diff --git a/src/lib/components/layout/FormLayout/FormLayoutCustomField.jsx b/src/lib/components/layout/FormLayout/FormLayoutCustomField.jsx
index e82ab5f3..c0b6ef84 100644
--- a/src/lib/components/layout/FormLayout/FormLayoutCustomField.jsx
+++ b/src/lib/components/layout/FormLayout/FormLayoutCustomField.jsx
@@ -1,31 +1,62 @@
 import PropTypes from 'prop-types';
 import React from 'react';
+import getRootSizeClassName from '../../../helpers/getRootSizeClassName';
+import getRootValidationStateClassName from '../../../helpers/getRootValidationStateClassName';
 import { withProviderContext } from '../../../provider';
 import styles from './FormLayoutCustomField.scss';
 
+const renderLabel = (id, label, labelForId) => {
+  if (labelForId && label) {
+    return (
+      <label
+        htmlFor={labelForId}
+        id={id && `${id}__label`}
+        className={styles.label}
+      >
+        {label}
+      </label>
+    );
+  }
+
+  if (label) {
+    return (
+      <div
+        id={id && `${id}__label`}
+        className={styles.label}
+      >
+        {label}
+      </div>
+    );
+  }
+
+  return null;
+};
+
 export const FormLayoutCustomField = ({
   children,
   fullWidth,
   id,
+  disabled,
+  innerFieldSize,
   label,
+  labelForId,
   layout,
+  required,
+  validationState,
 }) => (
   <div
     id={id}
-    className={`
-      ${styles.root}
-      ${fullWidth ? styles.isRootFullWidth : ''}
-      ${layout === 'vertical' ? styles.rootLayoutVertical : styles.rootLayoutHorizontal}
-    `.trim()}
+    className={[
+      styles.root,
+      fullWidth ? styles.isRootFullWidth : '',
+      layout === 'vertical' ? styles.rootLayoutVertical : styles.rootLayoutHorizontal,
+      disabled ? styles.isRootDisabled : '',
+      required ? styles.isRootRequired : '',
+      getRootSizeClassName(innerFieldSize, styles),
+      getRootValidationStateClassName(validationState, styles),
+    ].join(' ')}
   >
-    {label && (
-      <div
-        id={id && `${id}__label`}
-        className={styles.label}
-      >
-        {label}
-      </div>
-    )}
+    {renderLabel(id, label, labelForId)}
     <div
       id={id && `${id}__field`}
       className={styles.field}
@@ -37,10 +68,15 @@ export const FormLayoutCustomField = ({
 
 FormLayoutCustomField.defaultProps = {
   children: null,
+  disabled: false,
   fullWidth: false,
   id: undefined,
+  innerFieldSize: null,
   label: null,
+  labelForId: undefined,
   layout: 'vertical',
+  required: false,
+  validationState: null,
 };
 
 FormLayoutCustomField.propTypes = {
@@ -48,6 +84,10 @@ FormLayoutCustomField.propTypes = {
    * Custom HTML or React component(s).
    */
   children: PropTypes.node,
+  /**
+   * If `true`, label will be shown as disabled.
+   */
+  disabled: PropTypes.bool,
   /**
    * If `true`, the field will span the full width of its parent.
    */
@@ -56,14 +96,30 @@ FormLayoutCustomField.propTypes = {
    * ID of the root HTML element.
    */
   id: PropTypes.string,
+  /**
+   * Size of contained form field used to properly align label.
+   */
+  innerFieldSize: PropTypes.oneOf(['small', 'medium', 'large']),
   /**
    * Optional label of the field.
    */
   label: PropTypes.string,
+  /**
+   * Optional ID of labelled field to keep accessibility features.
+   */
+  labelForId: PropTypes.string,
   /**
    * Layout of the field, controlled by parent FormLayout.
    */
   layout: PropTypes.oneOf(['horizontal', 'vertical']),
+  /**
+   * If `true`, label will be styled as required.
+   */
+  required: PropTypes.bool,
+  /**
+   * Alter the field to provide feedback based on validation result.
+   */
+  validationState: PropTypes.oneOf(['invalid', 'valid', 'warning']),
 };
 
 export const FormLayoutCustomFieldWithContext = withProviderContext(FormLayoutCustomField, 'FormLayoutCustomField');
diff --git a/src/lib/components/layout/FormLayout/FormLayoutCustomField.scss b/src/lib/components/layout/FormLayout/FormLayoutCustomField.scss
index e7e74d16..476c1974 100644
--- a/src/lib/components/layout/FormLayout/FormLayoutCustomField.scss
+++ b/src/lib/components/layout/FormLayout/FormLayoutCustomField.scss
@@ -1,9 +1,36 @@
+@use '../../../styles/tools/form-fields/foundation';
 @use '../../../styles/tools/form-fields/box-field-layout';
+@use '../../../styles/tools/form-fields/box-field-sizes';
+@use '../../../styles/tools/form-fields/variants';
 
+// Foundation
 .root {
   @include box-field-layout.in-form-layout();
+  @include variants.visual(custom);
 }
 
+.label {
+  @include foundation.label();
+}
+
+.isRootRequired .label {
+  @include foundation.label-required();
+}
+
+// States
+.isRootStateInvalid {
+  @include variants.validation(invalid);
+}
+
+.isRootStateValid {
+  @include variants.validation(valid);
+}
+
+.isRootStateWarning {
+  @include variants.validation(warning);
+}
+
+// Layouts
 .rootLayoutVertical,
 .rootLayoutHorizontal {
   @include box-field-layout.vertical();
@@ -21,3 +48,16 @@
 .isRootFullWidth .field {
   justify-self: stretch;
 }
+
+// Sizes
+.rootSizeSmall {
+  @include box-field-sizes.size(small);
+}
+
+.rootSizeMedium {
+  @include box-field-sizes.size(medium);
+}
+
+.rootSizeLarge {
+  @include box-field-sizes.size(large);
+}
diff --git a/src/lib/components/layout/FormLayout/README.mdx b/src/lib/components/layout/FormLayout/README.mdx
index f3afa7f2..dcfd642b 100644
--- a/src/lib/components/layout/FormLayout/README.mdx
+++ b/src/lib/components/layout/FormLayout/README.mdx
@@ -253,15 +253,123 @@ FormLayout elements. FormLayoutCustomFields are designed to work solely inside
 the FormLayout component.
 
 <Playground>
-  <FormLayout fieldLayout="horizontal">
+  <FormLayout fieldLayout="horizontal" labelWidth="auto">
     <TextField id="my-text-field-custom-1" label="A form element" />
-    <FormLayoutCustomField label="Optional label">
-      <Placeholder bordered>Custom content</Placeholder>
+    <FormLayoutCustomField label="Optional custom field label">
+      <Placeholder bordered>Custom field content</Placeholder>
     </FormLayoutCustomField>
     <TextField id="my-text-field-custom-2" label="Another form element" />
   </FormLayout>
 </Playground>
 
+👉 While you can set FormLayoutCustomField as `disabled`, `valid` or `required`
+and its styles may affect contained form fields through CSS cascade, don't
+forget to mirror the aforementioned properties to the contained form fields too
+as API options as such are **not** inherited.
+
+### Label Alignment
+
+If you are in a situation with one or more box form fields inside your
+FormLayoutCustomField, you may want to have its label aligned with the fields
+inside. Since it's
+[not quite possible to do this automatically](https://github.com/react-ui-org/react-ui/issues/265)
+due to limited browser support, there is `innerFieldSize` option which accepts
+any of existing box field sizes (small, medium, or large) and is intended right
+for this task.
+
+<Playground>
+  <FormLayout fieldLayout="horizontal" labelWidth="auto">
+    <TextField id="my-text-field-custom-alignment-1" label="A form element" />
+    <FormLayoutCustomField
+      innerFieldSize="medium"
+      label="Custom field label aligned to inner text input"
+    >
+      <TextField
+        id="my-text-field-custom-alignment-2"
+        isLabelVisible={false}
+        label="A form element"
+        placeholder="Text field with invisible label"
+      />
+    </FormLayoutCustomField>
+    <TextField
+      id="my-text-field-custom-alignment-3"
+      label="Another form element"
+    />
+  </FormLayout>
+</Playground>
+
+### Validation States
+
+Custom fields support the same validation states as regular form fields to
+provide labels with optional feedback style.
+
+<Playground>
+  <FormLayout fieldLayout="horizontal" labelWidth="auto">
+    <TextField id="my-text-field-custom-validation-1" label="A form element" />
+    <FormLayoutCustomField
+      label="Custom field label in valid state"
+      validationState="valid"
+    >
+      <Placeholder bordered>Custom field content</Placeholder>
+    </FormLayoutCustomField>
+    <TextField
+      id="my-text-field-custom-validation-2"
+      label="Another form element"
+    />
+  </FormLayout>
+</Playground>
+
+### Accessibility
+
+If possible, use the `labelForId` option to provide ID of contained form field
+so the field remains accessible via custom field label.
+
+You can also specify size of contained form field so custom field label is
+properly vertically aligned.
+
+<Playground>
+  {() => {
+    const [isChecked, setIsChecked] = React.useState(false);
+    return (
+      <FormLayout fieldLayout="horizontal" labelWidth="auto">
+        <TextField
+          id="my-text-field-custom-accessibility-1"
+          label="A form element"
+        />
+        <FormLayoutCustomField
+          fullWidth
+          label="Custom field label aligned with medium form field"
+          labelForId="my-text-field-custom-accessibility-2"
+          innerFieldSize="medium"
+        >
+          <Toolbar align="middle" dense>
+            <ToolbarItem>
+              <TextField
+                id="my-text-field-custom-accessibility-2"
+                isLabelVisible={false}
+                label="A form element"
+                placeholder="Text field with invisible label"
+              />
+            </ToolbarItem>
+            <ToolbarItem>
+              <CheckboxField
+                changeHandler={() => setIsChecked(!isChecked)}
+                checked={isChecked}
+                id="my-checkbox-field-custom-accessibility-1"
+                label="Another form field"
+              />
+            </ToolbarItem>
+          </Toolbar>
+        </FormLayoutCustomField>
+        <TextField
+          id="my-text-field-custom-accessibility-3"
+          label="Another form element"
+        />
+      </FormLayout>
+    )
+  }}
+</Playground>
+
 ## Full Example
 
 This is a demo of all components supported by FormLayout.
@@ -403,7 +511,7 @@ This is a demo of all components supported by FormLayout.
 
 <Props table of={FormLayout} />
 
-### FormLayoutCustomField
+### FormLayoutCustomField API
 
 A place for custom content inside FormLayout.
 
@@ -417,3 +525,13 @@ A place for custom content inside FormLayout.
 | `--rui-form-layout-horizontal-label-limited-width`   | Label width in limited-width layout                          |
 | `--rui-form-layout-horizontal-label-default-width`   | Label width in the default layout                            |
 | `--rui-form-layout-row-gap`                          | Gap between individual rows                                  |
+
+### FormLayoutCustomField Theming
+
+FormLayoutCustomField can be styled using a small subset of
+[other form fields theming options](/customize/theming/forms).
+
+| Custom Property                                      | Description                                                  |
+|------------------------------------------------------|--------------------------------------------------------------|
+| `--rui-form-field-custom-default-surrounding-text-color` | Custom field label color in default state                |
+| `--rui-form-field-custom-disabled-surrounding-text-color` | Custom field label color in disabled-like state         |
diff --git a/src/lib/components/layout/FormLayout/__tests__/FormLayoutCustomField.test.jsx b/src/lib/components/layout/FormLayout/__tests__/FormLayoutCustomField.test.jsx
index a5a4d135..ec306860 100644
--- a/src/lib/components/layout/FormLayout/__tests__/FormLayoutCustomField.test.jsx
+++ b/src/lib/components/layout/FormLayout/__tests__/FormLayoutCustomField.test.jsx
@@ -28,10 +28,14 @@ describe('rendering', () => {
   it('renders correctly with all props', () => {
     const tree = shallow((
       <FormLayoutCustomField
+        disabled
         fullWidth
         label="Label"
+        labelForId="target-id"
         id="my-custom-field"
+        innerFieldSize="small"
         layout="horizontal"
+        required
       >
         <span>Custom text in form 1</span>
         <span>Custom text in form 2</span>
diff --git a/src/lib/components/layout/FormLayout/__tests__/__snapshots__/FormLayoutCustomField.test.jsx.snap b/src/lib/components/layout/FormLayout/__tests__/__snapshots__/FormLayoutCustomField.test.jsx.snap
index 2627acb1..84b40087 100644
--- a/src/lib/components/layout/FormLayout/__tests__/__snapshots__/FormLayoutCustomField.test.jsx.snap
+++ b/src/lib/components/layout/FormLayout/__tests__/__snapshots__/FormLayoutCustomField.test.jsx.snap
@@ -2,9 +2,7 @@
 
 exports[`rendering renders correctly with a single child 1`] = `
 <div
-  className="root
-      
-      rootLayoutVertical"
+  className="root  rootLayoutVertical    "
 >
   <div
     className="field"
@@ -18,17 +16,16 @@ exports[`rendering renders correctly with a single child 1`] = `
 
 exports[`rendering renders correctly with all props 1`] = `
 <div
-  className="root
-      isRootFullWidth
-      rootLayoutHorizontal"
+  className="root isRootFullWidth rootLayoutHorizontal isRootDisabled isRootRequired rootSizeSmall "
   id="my-custom-field"
 >
-  <div
+  <label
     className="label"
+    htmlFor="target-id"
     id="my-custom-field__label"
   >
     Label
-  </div>
+  </label>
   <div
     className="field"
     id="my-custom-field__field"
@@ -48,9 +45,7 @@ exports[`rendering renders correctly with all props 1`] = `
 
 exports[`rendering renders correctly with multiple children 1`] = `
 <div
-  className="root
-      
-      rootLayoutVertical"
+  className="root  rootLayoutVertical    "
 >
   <div
     className="field"
diff --git a/src/lib/styles/settings/_form-fields.scss b/src/lib/styles/settings/_form-fields.scss
index 60e9817c..d4d56730 100644
--- a/src/lib/styles/settings/_form-fields.scss
+++ b/src/lib/styles/settings/_form-fields.scss
@@ -30,6 +30,9 @@ $themeable-variant-states: (
   check: (
     default: (default, checked, disabled, checked-disabled),
   ),
+  custom: (
+    default: (default, disabled),
+  ),
   validation: (
     invalid: (default, checked, disabled, checked-disabled),
     valid: (default, checked, disabled, checked-disabled),
diff --git a/webpack.config.js b/webpack.config.js
index 2a0096b0..1a50f743 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -2,8 +2,8 @@ const path = require('path');
 const StyleLintPlugin = require('stylelint-webpack-plugin');
 const VisualizerPlugin = require('webpack-visualizer-plugin');
 
-const MAX_DEVELOPMENT_OUTPUT_SIZE = 2300000;
-const MAX_PRODUCTION_OUTPUT_SIZE = 270000;
+const MAX_DEVELOPMENT_OUTPUT_SIZE = 2400000;
+const MAX_PRODUCTION_OUTPUT_SIZE = 280000;
 
 module.exports = (env, argv) => ({
   devtool: argv.mode === 'production'