diff --git a/.changeset/fair-spies-rescue.md b/.changeset/fair-spies-rescue.md
new file mode 100644
index 0000000000..d7f1ea5275
--- /dev/null
+++ b/.changeset/fair-spies-rescue.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-scaffolder-backend-module-github': patch
+---
+
+Ensure `teamReviewers` list is unique before calling API
diff --git a/plugins/scaffolder-backend-module-github/src/actions/githubPullRequest.test.ts b/plugins/scaffolder-backend-module-github/src/actions/githubPullRequest.test.ts
index 23ac4bda45..c5b1038a01 100644
--- a/plugins/scaffolder-backend-module-github/src/actions/githubPullRequest.test.ts
+++ b/plugins/scaffolder-backend-module-github/src/actions/githubPullRequest.test.ts
@@ -377,7 +377,7 @@ describe('createPublishGithubPullRequestAction', () => {
         branchName: 'new-app',
         description: 'This PR is really good',
         reviewers: ['foobar'],
-        teamReviewers: ['team-foo'],
+        teamReviewers: ['team-foo', 'team-foo', 'team-bar'],
       };
 
       mockDir.setContent({ [workspacePath]: {} });
@@ -401,7 +401,7 @@ describe('createPublishGithubPullRequestAction', () => {
         repo: 'myrepo',
         pull_number: 123,
         reviewers: ['foobar'],
-        team_reviewers: ['team-foo'],
+        team_reviewers: ['team-foo', 'team-bar'],
       });
     });
 
diff --git a/plugins/scaffolder-backend-module-github/src/actions/githubPullRequest.ts b/plugins/scaffolder-backend-module-github/src/actions/githubPullRequest.ts
index 0763d4a474..2d8dc7ce8d 100644
--- a/plugins/scaffolder-backend-module-github/src/actions/githubPullRequest.ts
+++ b/plugins/scaffolder-backend-module-github/src/actions/githubPullRequest.ts
@@ -372,7 +372,7 @@ export const createPublishGithubPullRequestAction = (
         repo: pr.repo,
         pull_number: pr.number,
         reviewers,
-        team_reviewers: teamReviewers,
+        team_reviewers: teamReviewers ? [...new Set(teamReviewers)] : undefined,
       });
       const addedUsers = result.data.requested_reviewers?.join(', ') ?? '';
       const addedTeams = result.data.requested_teams?.join(', ') ?? '';