diff --git a/invenio_rdm_records/services/communities/service.py b/invenio_rdm_records/services/communities/service.py
index 613d168c8..92e26aa9d 100644
--- a/invenio_rdm_records/services/communities/service.py
+++ b/invenio_rdm_records/services/communities/service.py
@@ -387,7 +387,9 @@ def set_default(self, identity, id_, data, uow):
         )
         record = self.record_cls.pid.resolve(id_)
         self.require_permission(identity, "manage", record=record)
-        record.parent.communities.default = valid_data["default"]["id"]
+
+        default_community_id = valid_data.get("default", {}).get("id") or None
+        record.parent.communities.default = default_community_id
 
         uow.register(
             ParentRecordCommitOp(
diff --git a/invenio_rdm_records/services/schemas/parent/communities.py b/invenio_rdm_records/services/schemas/parent/communities.py
index 89007e243..05fde991e 100644
--- a/invenio_rdm_records/services/schemas/parent/communities.py
+++ b/invenio_rdm_records/services/schemas/parent/communities.py
@@ -15,7 +15,7 @@ class CommunitiesSchema(Schema):
     """Communities schema."""
 
     ids = fields.List(fields.String())
-    default = fields.String(attribute="default.id")
+    default = fields.String(attribute="default.id", allow_none=True)
     entries = fields.List(fields.Nested(CommunitySchema))
 
     @post_dump
diff --git a/tests/resources/test_resources_communities.py b/tests/resources/test_resources_communities.py
index db56027e2..1e2e5130e 100644
--- a/tests/resources/test_resources_communities.py
+++ b/tests/resources/test_resources_communities.py
@@ -7,7 +7,6 @@
 
 """Tests record's communities resources."""
 
-from contextlib import contextmanager
 from copy import deepcopy
 
 import pytest
diff --git a/tests/resources/test_resources_record_communities.py b/tests/resources/test_resources_record_communities.py
index a9812884f..2c9698496 100644
--- a/tests/resources/test_resources_record_communities.py
+++ b/tests/resources/test_resources_record_communities.py
@@ -1,3 +1,13 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2024 CERN.
+#
+# Invenio-RDM-Records is free software; you can redistribute it and/or modify
+# it under the terms of the MIT License; see LICENSE file for more details.
+
+"""Record communities resources tests."""
+
+
 def test_search_record_suggested_communities(
     client,
     community,
@@ -43,16 +53,15 @@ def test_search_record_suggested_communities(
     assert hits["total"] == 0
 
     # add record to a community
-    data = {
-        "communities": [
-            {"id": open_review_community.id},  # test with id
-        ]
-    }
     record = record_community.create_record()
     response = client.post(
         f"/records/{record.pid.pid_value}/communities",
         headers=headers,
-        json=data,
+        json={
+            "communities": [
+                {"id": open_review_community.id},  # test with id
+            ]
+        },
     )
 
     assert response.status_code == 200
@@ -69,3 +78,102 @@ def test_search_record_suggested_communities(
     hits = response.json["hits"]
     assert hits["total"] == 1
     assert hits["hits"][0]["id"] != open_review_community.id
+
+
+def test_set_default_community(
+    client,
+    headers,
+    curator,
+    inviter,
+    community,
+    open_review_community,
+    closed_review_community,
+    record_community,
+):
+    """Test setting a default community for a record."""
+    # Add the curator user to the open review community
+    inviter(curator.id, open_review_community.id, "curator")
+    record = record_community.create_record(uploader=curator)
+
+    # Login as the curator user
+    client = curator.login(client)
+
+    # Add the record to the open review community
+    resp = client.post(
+        f"/records/{record.pid.pid_value}/communities",
+        headers=headers,
+        json={"communities": [{"id": open_review_community.id}]},
+    )
+    assert resp.status_code == 200
+    assert not resp.json.get("errors")
+    processed = resp.json["processed"]
+    assert len(processed) == 1
+
+    def _assert_record_in_(communities, default=None):
+        resp = client.get(f"/records/{record.pid.pid_value}", headers=headers)
+        record_communities = resp.json["parent"]["communities"]
+        assert set(record_communities["ids"]) == communities
+        if default:
+            assert record_communities["default"] == default
+        else:
+            assert "default" not in record_communities
+
+    _assert_record_in_({community.id, open_review_community.id}, default=None)
+
+    # Set the default community to invalid values
+    resp = client.put(
+        f"/records/{record.pid.pid_value}/communities",
+        headers=headers,
+        json={"default": closed_review_community.id},
+    )
+    assert resp.status_code == 400
+    assert resp.json["message"] == (
+        "Cannot set community as the default. The record has not been added to the community."
+    )
+
+    # Set the default community to the open review community
+    resp = client.put(
+        f"/records/{record.pid.pid_value}/communities",
+        headers=headers,
+        json={"default": open_review_community.id},
+    )
+    assert resp.status_code == 200
+    assert resp.json["communities"]["default"] == open_review_community.id
+
+    _assert_record_in_(
+        {community.id, open_review_community.id},
+        default=open_review_community.id,
+    )
+
+    # Unset the default community
+    resp = client.put(
+        f"/records/{record.pid.pid_value}/communities",
+        headers=headers,
+        json={"default": None},
+    )
+    assert resp.status_code == 200
+    assert "default" not in resp.json["communities"]
+
+    _assert_record_in_({community.id, open_review_community.id}, default=None)
+
+    # Set the default community to the original community
+    resp = client.put(
+        f"/records/{record.pid.pid_value}/communities",
+        headers=headers,
+        json={"default": community.id},
+    )
+    assert resp.status_code == 200
+    assert resp.json["communities"]["default"] == community.id
+
+    _assert_record_in_({community.id, open_review_community.id}, default=community.id)
+
+    # Unset the default community using empty string (current wrong behaviour in the UI)
+    resp = client.put(
+        f"/records/{record.pid.pid_value}/communities",
+        headers=headers,
+        json={"default": ""},
+    )
+    assert resp.status_code == 200
+    assert "default" not in resp.json["communities"]
+
+    _assert_record_in_({community.id, open_review_community.id}, default=None)