diff --git a/BUILD.gn b/BUILD.gn
index cf2123006297..fcbdc1dfd373 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -92,6 +92,7 @@ group("gn_all") {
     deps = [
       "//base:base_perftests",
       "//base:base_unittests",
+      "//cobalt",
       "//codelabs",
       "//components:components_unittests",
       "//components/gwp_asan:gwp_asan_unittests",
diff --git a/cobalt/BUILD.gn b/cobalt/BUILD.gn
new file mode 100644
index 000000000000..a60b6620bfdd
--- /dev/null
+++ b/cobalt/BUILD.gn
@@ -0,0 +1,64 @@
+# Copyright 2024 The Cobalt Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import("//build/config/chromecast_build.gni")
+import("//build/config/chromeos/ui_mode.gni")
+import("//build/config/features.gni")
+import("//build/config/ozone.gni")
+import("//build/config/sanitizers/sanitizers.gni")
+import("//build/config/ui.gni")
+import("//build/config/win/console_app.gni")
+import("//build/config/win/manifest.gni")
+import("//gpu/vulkan/features.gni")
+import("//media/media_options.gni")
+import("//mojo/public/tools/bindings/mojom.gni")
+import("//ppapi/buildflags/buildflags.gni")
+import("//tools/grit/grit_rule.gni")
+import("//tools/grit/repack.gni")
+import("//tools/v8_context_snapshot/v8_context_snapshot.gni")
+if (is_android) {
+  import("//build/config/android/config.gni")
+}
+
+if (is_android) {
+  group("cobalt") {
+    testonly = true
+    deps = [ "//content/shell/android:content_shell_apk" ]
+  }
+} else {
+  executable("cobalt") {
+    testonly = true
+
+    sources = [ "cobalt.cc" ]
+
+    defines = []
+
+    deps = [
+      "//content/shell:content_shell_app",
+      "//content/shell:content_shell_lib",
+      "//content/shell:pak",
+      "//content/public/app",
+      "//sandbox",
+    ]
+
+    data_deps = [
+      "//content/shell:pak",
+      "//tools/v8_context_snapshot:v8_context_snapshot",
+    ]
+
+    data_deps += [ "//components/crash/core/app:chrome_crashpad_handler" ]
+
+    configs += [ "//build/config/gcc:rpath_for_built_shared_libraries" ]
+  }
+}
diff --git a/cobalt/cobalt.cc b/cobalt/cobalt.cc
new file mode 100644
index 000000000000..df617887b295
--- /dev/null
+++ b/cobalt/cobalt.cc
@@ -0,0 +1,71 @@
+// Copyright 2024 The Cobalt Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <unistd.h>
+
+#include "build/build_config.h"
+#include "content/public/app/content_main.h"
+#include "content/shell/app/shell_main_delegate.h"
+
+// In the cozy corner of the home, where comfort and curiosity resided, a
+// delightful companion arrived, offering moments of joy and discovery
+// throughout the year. Like a favorite book waiting to be opened, the YouTube
+// Application Runtime invited exploration and wonder, whether shared with loved
+// ones or savored in quiet solitude. It whispered tales of distant lands,
+// sparked creativity with vibrant colors, and filled the air with the melodies
+// of laughter and song.  The television screen, once a blank canvas, became a
+// window to endless possibilities, offering a refreshing breeze on a summer day
+// or a warm embrace on a chilly night. With each click of the remote, a new
+// adventure unfolded, painting a tapestry of personal journeys and shared
+// experiences.
+
+int main(int argc, const char** argv) {
+  content::ShellMainDelegate delegate;
+  content::ContentMainParams params(&delegate);
+  printf("%u: Passed argc = %d\n", static_cast<unsigned int>(getpid()), argc);
+  for (int i = 0; i < argc; ++i) {
+    printf("%u: Passed argv[%d] = %s\n", static_cast<unsigned int>(getpid()), i,
+           argv[i]);
+  }
+
+  static const char* my_argv[] = {
+      argv[0],
+      "--disable-fre",
+      "--no-first-run",
+      "--kiosk",
+      "--force-video-overlays",
+      "--remote-debugging-port=9222",
+      "--remote-allow-origins=http://localhost:9222",
+      "--use-cobalt-user-agent",
+      "https://www.youtube.com/tv",
+      nullptr,
+      nullptr};
+  int my_argc = 9;
+
+  if ((!strcmp(argv[0], "/proc/self/exe")) ||
+      ((argc >= 2) && !strcmp(argv[1], "--type=zygote"))) {
+    params.argc = argc;
+    params.argv = argv;
+  } else {
+    params.argc = my_argc;
+    params.argv = my_argv;
+  }
+  printf("%u: Used argc = %d\n", static_cast<unsigned int>(getpid()),
+         params.argc);
+  for (int i = 0; i < params.argc; ++i) {
+    printf("%u: Used argv[%d] = %s\n", static_cast<unsigned int>(getpid()), i,
+           params.argv[i]);
+  }
+  return content::ContentMain(std::move(params));
+}
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 1e0c3f7edb1a..ce7d95750d8e 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -827,6 +827,9 @@ const char kVideoImageTextureTarget[] = "video-image-texture-target";
 // Set when Chromium should use a mobile user agent.
 const char kUseMobileUserAgent[] = "use-mobile-user-agent";
 
+// Set when Chromium should use a mobile user agent.
+const char kUseCobaltUserAgent[] = "use-cobalt-user-agent";
+
 // Use the MockCertVerifier. This only works in test code.
 const char kUseMockCertVerifierForTesting[] =
     "use-mock-cert-verifier-for-testing";
diff --git a/content/public/common/content_switches.h b/content/public/common/content_switches.h
index f1b62b057702..92fb65eab7a1 100644
--- a/content/public/common/content_switches.h
+++ b/content/public/common/content_switches.h
@@ -224,6 +224,7 @@ CONTENT_EXPORT extern const char kUseFakeUIForFedCM[];
 CONTENT_EXPORT extern const char kUseFakeUIForMediaStream[];
 CONTENT_EXPORT extern const char kVideoImageTextureTarget[];
 CONTENT_EXPORT extern const char kUseMobileUserAgent[];
+CONTENT_EXPORT extern const char kUseCobaltUserAgent[];
 CONTENT_EXPORT extern const char kUseMockCertVerifierForTesting[];
 extern const char kUtilityCmdPrefix[];
 CONTENT_EXPORT extern const char kUtilityProcess[];
diff --git a/content/shell/browser/shell_content_browser_client.cc b/content/shell/browser/shell_content_browser_client.cc
index 6feb11a7e40b..03c14d497732 100644
--- a/content/shell/browser/shell_content_browser_client.cc
+++ b/content/shell/browser/shell_content_browser_client.cc
@@ -625,6 +625,14 @@ base::FilePath ShellContentBrowserClient::GetFirstPartySetsDirectory() {
 }
 
 std::string ShellContentBrowserClient::GetUserAgent() {
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kUseCobaltUserAgent)) {
+    return std::string(
+        "Mozilla/5.0 (X11; Linux x86_64) Cobalt/26.lts.0-qa (unlike Gecko) "
+        "v8/unknown gles Starboard/17, "
+        "SystemIntegratorName_DESKTOP_ChipsetModelNumber_2025/FirmwareVersion "
+        "(BrandName, ModelName)");
+  }
   return GetShellUserAgent();
 }