diff --git a/invenio_accounts/cli.py b/invenio_accounts/cli.py
index ff506d2c..fde055e6 100644
--- a/invenio_accounts/cli.py
+++ b/invenio_accounts/cli.py
@@ -3,6 +3,7 @@
 # This file is part of Invenio.
 # Copyright (C) 2015-2023 CERN.
 # Copyright (C) 2024 Graz University of Technology.
+# Copyright (C) 2024 KTH Royal Institute of Technology.
 #
 # Invenio is free software; you can redistribute it and/or modify it
 # under the terms of the MIT License; see LICENSE file for more details.
@@ -170,8 +171,14 @@ def users_deactivate(user):
 @with_appcontext
 def domains_create(domain):
     """Create domain."""
+    domain = domain.lower()
+
+    if DomainCategory.get(domain):
+        click.secho(f"Domain {domain} already exists.", fg="red")
+        return
+
     try:
-        domain_category = DomainCategory.create(domain.lower())
+        domain_category = DomainCategory.create(domain)
         db.session.merge(domain_category)
         db.session.commit()
     except Exception as error:
diff --git a/invenio_accounts/models.py b/invenio_accounts/models.py
index 7a411567..14163960 100644
--- a/invenio_accounts/models.py
+++ b/invenio_accounts/models.py
@@ -2,7 +2,7 @@
 #
 # This file is part of Invenio.
 # Copyright (C) 2015-2024 CERN.
-# Copyright (C) 2022 KTH Royal Institute of Technology
+# Copyright (C) 2022-2024 KTH Royal Institute of Technology.
 #
 # Invenio is free software; you can redistribute it and/or modify it
 # under the terms of the MIT License; see LICENSE file for more details.
@@ -526,7 +526,7 @@ class DomainCategory(db.Model):
 
     id = db.Column(db.Integer(), primary_key=True, autoincrement=True)
 
-    label = db.Column(db.String(255))
+    label = db.Column(db.String(255), unique=True)
 
     @classmethod
     def create(cls, label):
diff --git a/tests/test_cli.py b/tests/test_cli.py
index f1d3dc3b..ae130dce 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -2,6 +2,7 @@
 #
 # This file is part of Invenio.
 # Copyright (C) 2015-2018 CERN.
+# Copyright (C) 2024 KTH Royal Institute of Technology.
 #
 # Invenio is free software; you can redistribute it and/or modify it
 # under the terms of the MIT License; see LICENSE file for more details.
@@ -10,6 +11,7 @@
 """Module tests."""
 
 from invenio_accounts.cli import (
+    domains_create,
     roles_add,
     roles_create,
     roles_remove,
@@ -156,3 +158,28 @@ def test_cli_activate_deactivate(app):
     assert result.exit_code == 0
     result = runner.invoke(users_deactivate, ["a@test.org"])
     assert result.exit_code == 0
+
+
+def test_cli_createdomain(app):
+    """Test create domain CLI."""
+    runner = app.test_cli_runner()
+
+    # Create a domain successfully
+    result = runner.invoke(domains_create, ["mailprovider"])
+    assert result.exit_code == 0
+    assert "Domain mailprovider created successfully" in result.output
+
+    # Reject Creating the same domain again
+    result = runner.invoke(domains_create, ["mailprovider"])
+    assert result.exit_code == 0
+    assert "Domain mailprovider already exists." in result.output
+
+    # Create another domain successfully
+    result = runner.invoke(domains_create, ["kth.se"])
+    assert result.exit_code == 0
+    assert "Domain kth.se created successfully" in result.output
+
+    # Create a domain with a fancy case should be treated like others
+    result = runner.invoke(domains_create, ["MailPrOvIdEr"])
+    assert result.exit_code == 0
+    assert "Domain mailprovider already exists." in result.output
diff --git a/tests/test_models.py b/tests/test_models.py
index b5260a21..5bd5f660 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -3,7 +3,7 @@
 # This file is part of Invenio.
 # Copyright (C) 2015-2024 CERN.
 # Copyright (C)      2022 TU Wien.
-# Copyright (C) 2022 KTH Royal Institute of Technology
+# Copyright (C) 2022-2024 KTH Royal Institute of Technology.
 #
 # Invenio is free software; you can redistribute it and/or modify it
 # under the terms of the MIT License; see LICENSE file for more details.
@@ -14,6 +14,7 @@
 from invenio_db import db
 from marshmallow import Schema, fields
 from sqlalchemy import inspect
+from sqlalchemy.exc import IntegrityError
 
 from invenio_accounts import testutils
 from invenio_accounts.models import (
@@ -213,9 +214,25 @@ def test_domain_org(app):
 
 
 def test_domain_category(app):
+    """Test DomainCategory creation and retrieval."""
     c1 = DomainCategory.create("spammer")
     c2 = DomainCategory.create("organisation")
     db.session.commit()
 
     c = DomainCategory.get("spammer")
     assert c.label == "spammer"
+
+    # Try to create a duplicate category
+    with pytest.raises(IntegrityError):
+        duplicate_category = DomainCategory.create("spammer")
+        db.session.commit()
+    # Clean the state after the IntegrityError
+    db.session.rollback()
+
+    # Assert a valid category can still be created after the error
+    c3 = DomainCategory.create("company")
+    db.session.commit()
+
+    # Make sure the new category is correctly stored
+    c = DomainCategory.get("company")
+    assert c.label == "company"