diff --git a/browser/brave_shields/domain_block_page_browsertest.cc b/browser/brave_shields/domain_block_page_browsertest.cc
index 775df47c5650..75888d66a9a2 100644
--- a/browser/brave_shields/domain_block_page_browsertest.cc
+++ b/browser/brave_shields/domain_block_page_browsertest.cc
@@ -35,6 +35,7 @@ class DomainBlockTestBase : public AdBlockServiceTest {
         [&](const net::test_server::HttpRequest& request) {
           request_count_ += 1;
         }));
+    content::SetupCrossSiteRedirector(embedded_test_server());
     AdBlockServiceTest::SetUp();
   }
 
@@ -299,6 +300,37 @@ IN_PROC_BROWSER_TEST_F(DomainBlockTest, NoFetch) {
   ASSERT_EQ(0, request_count_);
 }
 
+IN_PROC_BROWSER_TEST_F(DomainBlockTest, NoThirdPartyInterstitial) {
+  ASSERT_TRUE(InstallDefaultAdBlockExtension());
+  ASSERT_TRUE(g_brave_browser_process->ad_block_custom_filters_service()
+                  ->UpdateCustomFilters("||b.com^$third-party"));
+
+  GURL url = embedded_test_server()->GetURL("a.com", "/simple_link.html");
+  GURL cross_url =
+      embedded_test_server()->GetURL("a.com", "/cross-site/b.com/simple.html");
+
+  // Navigate to a page on a.com. This should work normally.
+  NavigateTo(url);
+  ASSERT_FALSE(IsShowingInterstitial());
+
+  // Navigate to a page on the third-party b.com. There should be no
+  // interstitial shown.
+  EXPECT_EQ(true,
+            EvalJs(web_contents(), "clickLink('" + cross_url.spec() + "')"));
+  EXPECT_TRUE(WaitForLoadStop(web_contents()));
+
+  // No interstitial should be shown, since top-level requests are never
+  // third-party.
+  ASSERT_FALSE(IsShowingInterstitial());
+
+  // The default "blocked by an extension" interstitial also should not be
+  // shown. This would appear if the request was blocked by the network delegate
+  // helper.
+  const std::string location =
+      EvalJs(web_contents(), "window.location.href").ExtractString();
+  ASSERT_STRNE("chrome-error://chromewebdata/", location.c_str());
+}
+
 IN_PROC_BROWSER_TEST_F(DomainBlockDisabledTest, NoInterstitial) {
   ASSERT_TRUE(InstallDefaultAdBlockExtension());
   GURL url = embedded_test_server()->GetURL("a.com", "/simple.html");
diff --git a/browser/net/brave_ad_block_tp_network_delegate_helper.cc b/browser/net/brave_ad_block_tp_network_delegate_helper.cc
index af676839fe01..7cb480eeb77c 100644
--- a/browser/net/brave_ad_block_tp_network_delegate_helper.cc
+++ b/browser/net/brave_ad_block_tp_network_delegate_helper.cc
@@ -243,6 +243,13 @@ int OnBeforeURLRequest_AdBlockTPPreWork(const ResponseCallback& next_callback,
     return net::OK;
   }
 
+  // Requests for main frames are handled by DomainBlockNavigationThrottle,
+  // which can display a custom interstitial with an option to proceed if a
+  // block is made. We don't need to check these twice.
+  if (ctx->resource_type == blink::mojom::ResourceType::kMainFrame) {
+    return net::OK;
+  }
+
   OnBeforeURLRequestAdBlockTP(next_callback, ctx);
 
   return net::ERR_IO_PENDING;