diff --git a/changelogs/unreleased/rs-keep-divergent-refs-for-push.yml b/changelogs/unreleased/rs-keep-divergent-refs-for-push.yml
new file mode 100644
index 0000000000000000000000000000000000000000..d736230ac526a70c21ea93d9c2178fa511e854c6
--- /dev/null
+++ b/changelogs/unreleased/rs-keep-divergent-refs-for-push.yml
@@ -0,0 +1,5 @@
+---
+title: Don't push divergent remote branches with keep_divergent_refs
+merge_request: 1915
+author:
+type: added
diff --git a/internal/service/remote/update_remote_mirror_test.go b/internal/service/remote/update_remote_mirror_test.go
index 87e51eb8cdb9165e01b07a5bc0dc0379fa0aeac0..0cb8524a930d4c981681eb3333223e7511fff4e0 100644
--- a/internal/service/remote/update_remote_mirror_test.go
+++ b/internal/service/remote/update_remote_mirror_test.go
@@ -195,6 +195,10 @@ func TestSuccessfulUpdateRemoteMirrorRequestWithKeepDivergentRefs(t *testing.T)
 		{"remote", "add", remoteName, mirrorPath},
 		{"fetch", remoteName},
 
+		// Create a divergence by moving `master` to the HEAD of another branch
+		// ba3faa7d only exists on `after-create-delete-modify-move`
+		{"update-ref", "refs/heads/master", "ba3faa7dbecdb555c748b36e8bc0f427e69de5e7"},
+
 		// Delete a branch and a tag to ensure they're kept around in the mirror
 		{"branch", "-D", "not-merged-branch"},
 		{"tag", "-d", "v2.0.0"},
@@ -224,8 +228,30 @@ func TestSuccessfulUpdateRemoteMirrorRequestWithKeepDivergentRefs(t *testing.T)
 
 	mirrorRefs := string(testhelper.MustRunCommand(t, nil, "git", "-C", mirrorPath, "for-each-ref"))
 
+	// Verify `master` didn't get updated, since its HEAD is no longer an ancestor of remote's version
+	require.Contains(t, mirrorRefs, "1e292f8fedd741b75372e19097c76d327140c312 commit\trefs/heads/master")
+
+	// Verify refs deleted on the source stick around on the mirror
 	require.Contains(t, mirrorRefs, "refs/heads/not-merged-branch")
 	require.Contains(t, mirrorRefs, "refs/tags/v2.0.0")
+
+	// Re-run mirroring without KeepDivergentRefs
+	firstRequest.KeepDivergentRefs = false
+
+	stream, err = client.UpdateRemoteMirror(ctx)
+	require.NoError(t, err)
+	require.NoError(t, stream.Send(firstRequest))
+
+	_, err = stream.CloseAndRecv()
+	require.NoError(t, err)
+
+	mirrorRefs = string(testhelper.MustRunCommand(t, nil, "git", "-C", mirrorPath, "for-each-ref"))
+
+	// Verify `master` gets overwritten with the value from the source
+	require.Contains(t, mirrorRefs, "ba3faa7dbecdb555c748b36e8bc0f427e69de5e7 commit\trefs/heads/master")
+
+	// Verify a branch only on the mirror is now deleted
+	require.NotContains(t, mirrorRefs, "refs/heads/not-merged-branch")
 }
 
 func TestFailedUpdateRemoteMirrorRequestDueToValidation(t *testing.T) {
diff --git a/ruby/lib/gitlab/git/remote_mirror.rb b/ruby/lib/gitlab/git/remote_mirror.rb
index 9311a8b2568a9810a0d238d0175e5492f34878c8..2ad02bb261247841fc9a00fa793b427e94ed2eb5 100644
--- a/ruby/lib/gitlab/git/remote_mirror.rb
+++ b/ruby/lib/gitlab/git/remote_mirror.rb
@@ -60,7 +60,23 @@ module Gitlab
         local_refs.select do |ref_name, ref|
           remote_ref = remote_refs[ref_name]
 
-          remote_ref.nil? || ref.dereferenced_target != remote_ref.dereferenced_target
+          # Ref doesn't exist on the remote, it should be created
+          next true if remote_ref.nil?
+
+          local_target = ref.dereferenced_target
+          remote_target = remote_ref.dereferenced_target
+
+          if local_target == remote_target
+            # Ref is identical on the remote, no point mirroring
+            false
+          elsif @keep_divergent_refs
+            # Mirror the ref if its remote counterpart hasn't diverged
+            repository.ancestor?(remote_target&.id, local_target&.id)
+          else
+            # Attempt to overwrite whatever's on the remote; push rules and
+            # protected branches may still prevent this
+            true
+          end
         end
       end