diff --git a/github/github.go b/github/github.go
index a806e7b8030..6e4f138961e 100644
--- a/github/github.go
+++ b/github/github.go
@@ -1451,13 +1451,18 @@ func CheckResponse(r *http.Response) error {
 	switch {
 	case r.StatusCode == http.StatusUnauthorized && strings.HasPrefix(r.Header.Get(headerOTP), "required"):
 		return (*TwoFactorAuthError)(errorResponse)
-	case r.StatusCode == http.StatusForbidden && r.Header.Get(headerRateRemaining) == "0":
+	// Primary rate limit exceeded: GitHub returns 403 or 429 with X-RateLimit-Remaining: 0
+	// See: https://docs.github.com/en/rest/using-the-rest-api/rate-limits-for-the-rest-api
+	case (r.StatusCode == http.StatusForbidden || r.StatusCode == http.StatusTooManyRequests) &&
+		r.Header.Get(headerRateRemaining) == "0":
 		return &RateLimitError{
 			Rate:     parseRate(r),
 			Response: errorResponse.Response,
 			Message:  errorResponse.Message,
 		}
-	case r.StatusCode == http.StatusForbidden &&
+	// Secondary rate limit exceeded: GitHub returns 403 or 429 with specific documentation_url
+	// See: https://docs.github.com/en/rest/using-the-rest-api/rate-limits-for-the-rest-api#about-secondary-rate-limits
+	case (r.StatusCode == http.StatusForbidden || r.StatusCode == http.StatusTooManyRequests) &&
 		(strings.HasSuffix(errorResponse.DocumentationURL, "#abuse-rate-limits") ||
 			strings.HasSuffix(errorResponse.DocumentationURL, "secondary-rate-limits")):
 		abuseRateLimitError := &AbuseRateLimitError{
diff --git a/github/github_test.go b/github/github_test.go
index c6f6941a65b..b95abc4d7b9 100644
--- a/github/github_test.go
+++ b/github/github_test.go
@@ -2182,6 +2182,77 @@ func TestCheckResponse_AbuseRateLimit(t *testing.T) {
 	}
 }
 
+// TestCheckResponse_RateLimit_TooManyRequests tests that HTTP 429 with
+// X-RateLimit-Remaining: 0 is correctly detected as RateLimitError.
+// GitHub API can return either 403 or 429 for rate limiting.
+// See: https://docs.github.com/en/rest/using-the-rest-api/rate-limits-for-the-rest-api
+func TestCheckResponse_RateLimit_TooManyRequests(t *testing.T) {
+	t.Parallel()
+	res := &http.Response{
+		Request:    &http.Request{},
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body: io.NopCloser(strings.NewReader(`{"message":"m",
+			"documentation_url": "url"}`)),
+	}
+	res.Header.Set(headerRateLimit, "60")
+	res.Header.Set(headerRateRemaining, "0")
+	res.Header.Set(headerRateUsed, "60")
+	res.Header.Set(headerRateReset, "243424")
+	res.Header.Set(headerRateResource, "core")
+
+	var err *RateLimitError
+	errors.As(CheckResponse(res), &err)
+
+	if err == nil {
+		t.Error("Expected error response.")
+	}
+
+	want := &RateLimitError{
+		Rate:     parseRate(res),
+		Response: res,
+		Message:  "m",
+	}
+	if !errors.Is(err, want) {
+		t.Errorf("Error = %#v, want %#v", err, want)
+	}
+}
+
+// TestCheckResponse_AbuseRateLimit_TooManyRequests tests that HTTP 429 with
+// secondary rate limit documentation_url is correctly detected as AbuseRateLimitError.
+// GitHub API can return either 403 or 429 for secondary rate limits.
+// See: https://docs.github.com/en/rest/using-the-rest-api/rate-limits-for-the-rest-api#about-secondary-rate-limits
+func TestCheckResponse_AbuseRateLimit_TooManyRequests(t *testing.T) {
+	t.Parallel()
+	res := &http.Response{
+		Request:    &http.Request{},
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body: io.NopCloser(strings.NewReader(`{"message":"m",
+			"documentation_url": "https://docs.github.com/rest/overview/rate-limits-for-the-rest-api#about-secondary-rate-limits"}`)),
+	}
+	res.Header.Set(headerRetryAfter, "60")
+
+	var err *AbuseRateLimitError
+	errors.As(CheckResponse(res), &err)
+
+	if err == nil {
+		t.Fatal("Expected error response.")
+	}
+
+	if err.Response != res {
+		t.Errorf("Response = %v, want %v", err.Response, res)
+	}
+	if err.Message != "m" {
+		t.Errorf("Message = %q, want %q", err.Message, "m")
+	}
+	if err.RetryAfter == nil {
+		t.Error("Expected RetryAfter to be set")
+	} else if *err.RetryAfter != 60*time.Second {
+		t.Errorf("RetryAfter = %v, want %v", *err.RetryAfter, 60*time.Second)
+	}
+}
+
 func TestCheckResponse_RedirectionError(t *testing.T) {
 	t.Parallel()
 	urlStr := "/foo/bar"