diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index 4b7ab1b4d2aecc..f99988d8992892 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -3726,7 +3726,6 @@ std::wstring ChromeContentBrowserClient::GetAppContainerSidForSandboxType(
     case sandbox::policy::SandboxType::kPrintCompositor:
     case sandbox::policy::SandboxType::kAudio:
     case sandbox::policy::SandboxType::kSpeechRecognition:
-    case sandbox::policy::SandboxType::kProxyResolver:
     case sandbox::policy::SandboxType::kPdfConversion:
     case sandbox::policy::SandboxType::kService:
     case sandbox::policy::SandboxType::kIconReader:
@@ -3793,7 +3792,6 @@ bool ChromeContentBrowserClient::PreSpawnChild(
     case sandbox::policy::SandboxType::kPrintCompositor:
     case sandbox::policy::SandboxType::kAudio:
     case sandbox::policy::SandboxType::kSpeechRecognition:
-    case sandbox::policy::SandboxType::kProxyResolver:
     case sandbox::policy::SandboxType::kPdfConversion:
     case sandbox::policy::SandboxType::kService:
     case sandbox::policy::SandboxType::kIconReader:
diff --git a/content/browser/utility_sandbox_delegate.cc b/content/browser/utility_sandbox_delegate.cc
index bab0b28901a8d8..ab6cf1bdbfba4d 100644
--- a/content/browser/utility_sandbox_delegate.cc
+++ b/content/browser/utility_sandbox_delegate.cc
@@ -40,7 +40,6 @@ UtilitySandboxedProcessLauncherDelegate::
       sandbox_type_ ==
           sandbox::policy::SandboxType::kNoSandboxAndElevatedPrivileges ||
       sandbox_type_ == sandbox::policy::SandboxType::kXrCompositing ||
-      sandbox_type_ == sandbox::policy::SandboxType::kProxyResolver ||
       sandbox_type_ == sandbox::policy::SandboxType::kPdfConversion ||
       sandbox_type_ == sandbox::policy::SandboxType::kIconReader ||
       sandbox_type_ == sandbox::policy::SandboxType::kMediaFoundationCdm ||
diff --git a/content/browser/utility_sandbox_delegate_win.cc b/content/browser/utility_sandbox_delegate_win.cc
index 6eeb875e8b50f5..ed2915e921cd1d 100644
--- a/content/browser/utility_sandbox_delegate_win.cc
+++ b/content/browser/utility_sandbox_delegate_win.cc
@@ -195,13 +195,6 @@ bool UtilitySandboxedProcessLauncherDelegate::PreSpawnTarget(
       return false;
   }
 
-  if (sandbox_type_ == sandbox::policy::SandboxType::kProxyResolver) {
-    sandbox::MitigationFlags flags = policy->GetDelayedProcessMitigations();
-    flags |= sandbox::MITIGATION_DYNAMIC_CODE_DISABLE;
-    if (sandbox::SBOX_ALL_OK != policy->SetDelayedProcessMitigations(flags))
-      return false;
-  }
-
   if (sandbox_type_ == sandbox::policy::SandboxType::kSpeechRecognition) {
     policy->SetDelayedIntegrityLevel(sandbox::INTEGRITY_LEVEL_LOW);
     policy->SetIntegrityLevel(sandbox::INTEGRITY_LEVEL_LOW);
diff --git a/sandbox/policy/mojom/sandbox.mojom b/sandbox/policy/mojom/sandbox.mojom
index 27d77c74081e6d..16be6497097179 100644
--- a/sandbox/policy/mojom/sandbox.mojom
+++ b/sandbox/policy/mojom/sandbox.mojom
@@ -67,10 +67,6 @@ enum Sandbox {
   [EnableIf=is_win]
   kPdfConversion,
 
-  // Like kUtility but also disables dynamic code.
-  [EnableIf=is_win]
-  kProxyResolver,
-
   // |kXrCompositing| hosts XR Device Service on Windows.
   [EnableIf=is_win]
   kXrCompositing,
diff --git a/sandbox/policy/sandbox_type.cc b/sandbox/policy/sandbox_type.cc
index b79692a1faa0f1..be659d6e6eee68 100644
--- a/sandbox/policy/sandbox_type.cc
+++ b/sandbox/policy/sandbox_type.cc
@@ -27,7 +27,6 @@ bool IsUnsandboxedSandboxType(SandboxType sandbox_type) {
       return true;
     case SandboxType::kXrCompositing:
       return !base::FeatureList::IsEnabled(features::kXRSandbox);
-    case SandboxType::kProxyResolver:
     case SandboxType::kPdfConversion:
     case SandboxType::kIconReader:
     case SandboxType::kMediaFoundationCdm:
@@ -126,7 +125,6 @@ void SetCommandLineFlagsForSandboxType(base::CommandLine* command_line,
 #endif
 #if defined(OS_WIN)
     case SandboxType::kXrCompositing:
-    case SandboxType::kProxyResolver:
     case SandboxType::kPdfConversion:
     case SandboxType::kIconReader:
     case SandboxType::kMediaFoundationCdm:
@@ -263,8 +261,6 @@ std::string StringFromUtilitySandboxType(SandboxType sandbox_type) {
 #if defined(OS_WIN)
     case SandboxType::kXrCompositing:
       return switches::kXrCompositingSandbox;
-    case SandboxType::kProxyResolver:
-      return switches::kProxyResolverSandbox;
     case SandboxType::kPdfConversion:
       return switches::kPdfConversionSandbox;
     case SandboxType::kIconReader:
@@ -339,8 +335,6 @@ SandboxType UtilitySandboxTypeFromString(const std::string& sandbox_string) {
 #if defined(OS_WIN)
   if (sandbox_string == switches::kXrCompositingSandbox)
     return SandboxType::kXrCompositing;
-  if (sandbox_string == switches::kProxyResolverSandbox)
-    return SandboxType::kProxyResolver;
   if (sandbox_string == switches::kPdfConversionSandbox)
     return SandboxType::kPdfConversion;
   if (sandbox_string == switches::kIconReaderSandbox)
diff --git a/sandbox/policy/sandbox_type.h b/sandbox/policy/sandbox_type.h
index 8380e0a10a5c78..29a2c9079853d6 100644
--- a/sandbox/policy/sandbox_type.h
+++ b/sandbox/policy/sandbox_type.h
@@ -34,9 +34,6 @@ enum class SandboxType {
   // The XR Compositing process.
   kXrCompositing,
 
-  // The proxy resolver process.
-  kProxyResolver,
-
   // The PDF conversion service process used in printing.
   kPdfConversion,
 
@@ -155,8 +152,6 @@ inline constexpr sandbox::policy::SandboxType MapToSandboxType(
       return sandbox::policy::SandboxType::kNoSandboxAndElevatedPrivileges;
     case sandbox::mojom::Sandbox::kPdfConversion:
       return sandbox::policy::SandboxType::kPdfConversion;
-    case sandbox::mojom::Sandbox::kProxyResolver:
-      return sandbox::policy::SandboxType::kProxyResolver;
     case sandbox::mojom::Sandbox::kXrCompositing:
       return sandbox::policy::SandboxType::kXrCompositing;
 #endif  // OS_WIN
diff --git a/sandbox/policy/sandbox_type_unittest.cc b/sandbox/policy/sandbox_type_unittest.cc
index dffb01208f1ccc..c5a36cc3221ba5 100644
--- a/sandbox/policy/sandbox_type_unittest.cc
+++ b/sandbox/policy/sandbox_type_unittest.cc
@@ -100,12 +100,6 @@ TEST(SandboxTypeTest, Utility) {
   EXPECT_EQ(SandboxType::kXrCompositing,
             SandboxTypeFromCommandLine(command_line10));
 
-  base::CommandLine command_line11(command_line);
-  SetCommandLineFlagsForSandboxType(&command_line11,
-                                    SandboxType::kProxyResolver);
-  EXPECT_EQ(SandboxType::kProxyResolver,
-            SandboxTypeFromCommandLine(command_line11));
-
   base::CommandLine command_line12(command_line);
   SetCommandLineFlagsForSandboxType(&command_line12,
                                     SandboxType::kPdfConversion);
diff --git a/sandbox/policy/switches.cc b/sandbox/policy/switches.cc
index 9ab64bce09c14f..387bab6dcacdfd 100644
--- a/sandbox/policy/switches.cc
+++ b/sandbox/policy/switches.cc
@@ -40,7 +40,6 @@ const char kVideoCaptureSandbox[] = "video_capture";
 
 #if defined(OS_WIN)
 const char kPdfConversionSandbox[] = "pdf_conversion";
-const char kProxyResolverSandbox[] = "proxy_resolver";
 const char kXrCompositingSandbox[] = "xr_compositing";
 const char kIconReaderSandbox[] = "icon_reader";
 const char kMediaFoundationCdmSandbox[] = "mf_cdm";
diff --git a/sandbox/policy/switches.h b/sandbox/policy/switches.h
index 1f7dc94681bd7c..692de02814ac8b 100644
--- a/sandbox/policy/switches.h
+++ b/sandbox/policy/switches.h
@@ -41,7 +41,6 @@ SANDBOX_POLICY_EXPORT extern const char kVideoCaptureSandbox[];
 
 #if defined(OS_WIN)
 SANDBOX_POLICY_EXPORT extern const char kPdfConversionSandbox[];
-SANDBOX_POLICY_EXPORT extern const char kProxyResolverSandbox[];
 SANDBOX_POLICY_EXPORT extern const char kXrCompositingSandbox[];
 SANDBOX_POLICY_EXPORT extern const char kIconReaderSandbox[];
 SANDBOX_POLICY_EXPORT extern const char kMediaFoundationCdmSandbox[];
diff --git a/sandbox/policy/win/sandbox_win.cc b/sandbox/policy/win/sandbox_win.cc
index c2342db7a860c4..9b736099479da8 100644
--- a/sandbox/policy/win/sandbox_win.cc
+++ b/sandbox/policy/win/sandbox_win.cc
@@ -1222,8 +1222,6 @@ std::string SandboxWin::GetSandboxTypeInEnglish(SandboxType sandbox_type) {
       return "Audio";
     case SandboxType::kSpeechRecognition:
       return "Speech Recognition";
-    case SandboxType::kProxyResolver:
-      return "Proxy Resolver";
     case SandboxType::kPdfConversion:
       return "PDF Conversion";
     case SandboxType::kMediaFoundationCdm:
diff --git a/services/proxy_resolver/public/mojom/proxy_resolver.mojom b/services/proxy_resolver/public/mojom/proxy_resolver.mojom
index 3906b7953a0e16..593e7a97605034 100644
--- a/services/proxy_resolver/public/mojom/proxy_resolver.mojom
+++ b/services/proxy_resolver/public/mojom/proxy_resolver.mojom
@@ -81,20 +81,13 @@ interface ProxyResolverRequestClient {
              pending_remote<HostResolverRequestClient> client);
 };
 
-// Note: On Android this lives in-process in the browser.
-[EnableIf=is_win]
-const sandbox.mojom.Sandbox kProxyResolverSandbox
-  = sandbox.mojom.Sandbox.kProxyResolver;
-[EnableIfNot=is_win]
-const sandbox.mojom.Sandbox kProxyResolverSandbox
-  = sandbox.mojom.Sandbox.kUtility;
-
 // Creates a ProxyResolver that uses the provided PAC script. The ProxyResolver
 // will remain valid even after the ProxyResolverFactory has been destroyed.
 //
 // Destroying |client| before its ReportResult method is invoked may cancel
 // creation of the ProxyResolverFactory.
-[ServiceSandbox=kProxyResolverSandbox]
+// Note: on Android this lives in the browser process.
+[ServiceSandbox=sandbox.mojom.Sandbox.kService]
 interface ProxyResolverFactory {
   CreateResolver(string pac_script,
                  pending_receiver<ProxyResolver> receiver,