diff --git a/chrome/browser/ui/web_applications/web_app_browsertest.cc b/chrome/browser/ui/web_applications/web_app_browsertest.cc
index bd8979f36112bc..278a4921afb223 100644
--- a/chrome/browser/ui/web_applications/web_app_browsertest.cc
+++ b/chrome/browser/ui/web_applications/web_app_browsertest.cc
@@ -1913,7 +1913,13 @@ class WebAppBrowserTest_FileHandler : public WebAppBrowserTest {
   base::test::ScopedFeatureList feature_list_;
 };
 
-IN_PROC_BROWSER_TEST_F(WebAppBrowserTest_FileHandler, WebAppFileHandler) {
+// TODO(crbug.com/1270961): Flaky on Win and Mac.
+#if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_MAC)
+#define MAYBE_WebAppFileHandler DISABLED_WebAppFileHandler
+#else
+#define MAYBE_WebAppFileHandler WebAppFileHandler
+#endif
+IN_PROC_BROWSER_TEST_F(WebAppBrowserTest_FileHandler, MAYBE_WebAppFileHandler) {
   os_hooks_suppress_.reset();
   base::ScopedAllowBlockingForTesting allow_blocking;