diff --git a/actions/setup/js/dismiss_pull_request_review.cjs b/actions/setup/js/dismiss_pull_request_review.cjs
index fa644a29413..1a72bf55b3f 100644
--- a/actions/setup/js/dismiss_pull_request_review.cjs
+++ b/actions/setup/js/dismiss_pull_request_review.cjs
@@ -225,12 +225,31 @@ async function main(config = {}) {
         };
       }
 
-      const { data: review } = await githubClient.rest.pulls.getReview({
-        owner,
-        repo,
-        pull_number: pullRequestNumber,
-        review_id: reviewId,
-      });
+      let review;
+      try {
+        const { data } = await githubClient.rest.pulls.getReview({
+          owner,
+          repo,
+          pull_number: pullRequestNumber,
+          review_id: reviewId,
+        });
+        review = data;
+      } catch (getReviewError) {
+        if (getReviewError?.status === 404) {
+          return {
+            success: true,
+            skipped: true,
+            reason: "review no longer exists",
+            review_id: reviewId,
+            pull_request_number: pullRequestNumber,
+            repo: `${owner}/${repo}`,
+          };
+        }
+        if (getReviewError && typeof getReviewError.message === "string") {
+          getReviewError.message = `Failed to fetch review ${reviewId} on ${owner}/${repo}#${pullRequestNumber}: ` + getReviewError.message;
+        }
+        throw getReviewError;
+      }
 
       const reviewAuthorLogin = review?.user?.login;
       const reviewAuthorType = typeof review?.user?.type === "string" ? review.user.type.trim() : "";
diff --git a/actions/setup/js/dismiss_pull_request_review.test.cjs b/actions/setup/js/dismiss_pull_request_review.test.cjs
index 039665c7495..7d71200a9b2 100644
--- a/actions/setup/js/dismiss_pull_request_review.test.cjs
+++ b/actions/setup/js/dismiss_pull_request_review.test.cjs
@@ -365,4 +365,39 @@ describe("dismiss_pull_request_review", () => {
     expect(result.error).toContain("truncated");
     expect(mockListReviews).toHaveBeenCalledTimes(10);
   });
+
+  it("returns skipped no-op when getReview returns 404 for an explicit review_id", async () => {
+    const notFoundError = Object.assign(new Error("Not Found"), { status: 404 });
+    mockGetReview.mockRejectedValueOnce(notFoundError);
+
+    const result = await handler({
+      type: "dismiss_pull_request_review",
+      review_id: 123,
+      justification: "This stale review no longer reflects the updated implementation.",
+    });
+
+    expect(result.success).toBe(true);
+    expect(result.skipped).toBe(true);
+    expect(result.reason).toContain("review no longer exists");
+    expect(result.review_id).toBe(123);
+    expect(result.pull_request_number).toBe(42);
+    expect(result.repo).toBe("test-owner/test-repo");
+    expect(mockDismissReview).not.toHaveBeenCalled();
+  });
+
+  it("fails with review context when getReview returns a non-404 error", async () => {
+    const serverError = Object.assign(new Error("Internal Server Error"), { status: 500 });
+    mockGetReview.mockRejectedValueOnce(serverError);
+
+    const result = await handler({
+      type: "dismiss_pull_request_review",
+      review_id: 123,
+      justification: "This stale review no longer reflects the updated implementation.",
+    });
+
+    expect(result.success).toBe(false);
+    expect(result.error).toContain("Failed to fetch review 123 on test-owner/test-repo#42");
+    expect(result.error).toContain("Internal Server Error");
+    expect(mockDismissReview).not.toHaveBeenCalled();
+  });
 });