diff --git a/changelogs/fragments/11851-gitlab-project-members-ambiguous.yml b/changelogs/fragments/11851-gitlab-project-members-ambiguous.yml
new file mode 100644
index 0000000000..f622144f18
--- /dev/null
+++ b/changelogs/fragments/11851-gitlab-project-members-ambiguous.yml
@@ -0,0 +1,4 @@
+bugfixes:
+  - gitlab_project_members - fail with a clear error when multiple projects match the given name, instead of silently operating on the first result
+    (https://github.com/ansible-collections/community.general/issues/2767,
+    https://github.com/ansible-collections/community.general/pull/11851).
diff --git a/plugins/modules/gitlab_project_members.py b/plugins/modules/gitlab_project_members.py
index 1bd759abce..4c3c9c080e 100644
--- a/plugins/modules/gitlab_project_members.py
+++ b/plugins/modules/gitlab_project_members.py
@@ -179,8 +179,15 @@ class GitLabProjectMembers:
             return project_exists.id
         except gitlab.exceptions.GitlabGetError:
             project_exists = self._gitlab.projects.list(search=project_name, all=False)
-            if project_exists:
+            if len(project_exists) == 1:
                 return project_exists[0].id
+            if len(project_exists) > 1:
+                self._module.fail_json(
+                    msg=(
+                        f"More than one project matches '{project_name}'. "
+                        "Use the full path ('group/project') to disambiguate."
+                    )
+                )
 
     def get_user_id(self, gitlab_user):
         user_exists = self._gitlab.users.list(username=gitlab_user, all=False)