diff --git a/dotnet/Templates/Microsoft.MacCatalyst.Templates/maccatalysttest/csharp/Main.cs b/dotnet/Templates/Microsoft.MacCatalyst.Templates/maccatalysttest/csharp/Main.cs
index c66e487fc13f..4ea38ded034b 100644
--- a/dotnet/Templates/Microsoft.MacCatalyst.Templates/maccatalysttest/csharp/Main.cs
+++ b/dotnet/Templates/Microsoft.MacCatalyst.Templates/maccatalysttest/csharp/Main.cs
@@ -63,7 +63,13 @@ public void WillConnect (UIScene scene, UISceneSession session, UISceneConnectio
 				var documentsPath = Environment.GetFolderPath (Environment.SpecialFolder.MyDocuments);
 				var resultsPath = Path.Combine (documentsPath, "TestResults");
 
+				// Forward args from 'dotnet test', which sends the MTP protocol config
+				// (--server / --dotnet-test-pipe) via the command line.
+				// Environment.GetCommandLineArgs()[0] is the executable path, not an argument.
+				string [] cliArgs = Environment.GetCommandLineArgs ();
+				string [] mtpArgs = cliArgs.Length > 1 ? cliArgs [1..] : [];
 				var builder = await TestApplication.CreateBuilderAsync ([
+					.. mtpArgs,
 					"--results-directory", resultsPath,
 					"--report-trx"
 				]);
diff --git a/dotnet/Templates/Microsoft.macOS.Templates/macostest/csharp/Main.cs b/dotnet/Templates/Microsoft.macOS.Templates/macostest/csharp/Main.cs
index 3c3c16808d33..d829f575772e 100644
--- a/dotnet/Templates/Microsoft.macOS.Templates/macostest/csharp/Main.cs
+++ b/dotnet/Templates/Microsoft.macOS.Templates/macostest/csharp/Main.cs
@@ -52,7 +52,13 @@ public override void DidFinishLaunching (NSNotification notification)
 				var documentsPath = Environment.GetFolderPath (Environment.SpecialFolder.MyDocuments);
 				var resultsPath = Path.Combine (documentsPath, "TestResults");
 
+				// Forward args from 'dotnet test', which sends the MTP protocol config
+				// (--server / --dotnet-test-pipe) via the command line.
+				// Environment.GetCommandLineArgs()[0] is the executable path, not an argument.
+				string [] cliArgs = Environment.GetCommandLineArgs ();
+				string [] mtpArgs = cliArgs.Length > 1 ? cliArgs [1..] : [];
 				var builder = await TestApplication.CreateBuilderAsync ([
+					.. mtpArgs,
 					"--results-directory", resultsPath,
 					"--report-trx"
 				]);
diff --git a/dotnet/targets/Xamarin.Shared.Sdk.MSTest.props b/dotnet/targets/Xamarin.Shared.Sdk.MSTest.props
index 83ced6200365..63f64f433235 100644
--- a/dotnet/targets/Xamarin.Shared.Sdk.MSTest.props
+++ b/dotnet/targets/Xamarin.Shared.Sdk.MSTest.props
@@ -11,6 +11,14 @@
 		<GenerateTestingPlatformEntryPoint Condition="'$(GenerateTestingPlatformEntryPoint)' == ''">false</GenerateTestingPlatformEntryPoint>
 		<!-- Suppress trimmer warnings from test framework dependencies (e.g. Microsoft.ApplicationInsights) -->
 		<SuppressTrimAnalysisWarnings Condition="'$(SuppressTrimAnalysisWarnings)' == ''">true</SuppressTrimAnalysisWarnings>
+		<!--
+			On macOS and Mac Catalyst 'dotnet run/test' launches the app via 'open' by default,
+			which goes through LaunchServices and does not propagate the parent process's
+			environment variables or reliably forward CLI arguments to the app. That breaks
+			the Microsoft.Testing.Platform (MTP) handshake that 'dotnet test' relies on.
+			Launching the app binary directly avoids the problem.
+		-->
+		<RunWithOpen Condition="'$(RunWithOpen)' == ''">false</RunWithOpen>
 	</PropertyGroup>
 	<ItemGroup>
 		<!-- Disable ANSI escape codes in MSTest output, as they appear as garbled text in simulator/device logs -->
diff --git a/tests/dotnet/UnitTests/DotNetTestTest.cs b/tests/dotnet/UnitTests/DotNetTestTest.cs
index fed4f817a74b..5b1faf96e471 100644
--- a/tests/dotnet/UnitTests/DotNetTestTest.cs
+++ b/tests/dotnet/UnitTests/DotNetTestTest.cs
@@ -13,10 +13,8 @@ public class DotNetTestTest : TestBaseClass {
 		[Test]
 		[TestCase (ApplePlatform.iOS, "iostest")]
 		[TestCase (ApplePlatform.TVOS, "tvostest")]
-		// macOS and Mac Catalyst don't use mlaunch (they use 'open' via Desktop.targets),
-		// so MTP support requires a different approach for these platforms.
-		// [TestCase (ApplePlatform.MacCatalyst, "maccatalysttest")]
-		// [TestCase (ApplePlatform.MacOSX, "macostest")]
+		[TestCase (ApplePlatform.MacCatalyst, "maccatalysttest")]
+		[TestCase (ApplePlatform.MacOSX, "macostest")]
 		public void DotNetTest (ApplePlatform platform, string template)
 		{
 			Configuration.IgnoreIfIgnoredPlatform (platform);
@@ -26,24 +24,21 @@ public void DotNetTest (ApplePlatform platform, string template)
 			DotNet.AssertNew (outputDir, template);
 			var proj = Path.Combine (outputDir, $"{template}.csproj");
 
-			// Boot a simulator so that ComputeRunArguments can find a device
+			var isDesktop = platform == ApplePlatform.MacOSX || platform == ApplePlatform.MacCatalyst;
 			var log = ConsoleLogger.Instance;
 			var simService = new SimulatorService (log);
-			var runtimeService = new RuntimeService (log);
-			var device = GetOrCreateDevice (platform, simService, runtimeService);
+			SimulatorDeviceInfo? device = null;
 
-			if (!device.IsBooted)
-				Assert.That (simService.Boot (device.Udid), Is.True, $"Failed to boot simulator {device.Udid}.");
+			if (!isDesktop) {
+				// Boot a simulator so that ComputeRunArguments can find a device
+				var runtimeService = new RuntimeService (log);
+				device = GetOrCreateDevice (platform, simService, runtimeService);
 
-			try {
-				// dotnet test internally calls ComputeRunArguments via MSBuild API without
-				// forwarding /p: properties, so we must set them in the project file directly.
-				var csproj = File.ReadAllText (proj);
-				csproj = csproj.Replace (
-					"</PropertyGroup>",
-					$"  <UseFloatingTargetPlatformVersion>true</UseFloatingTargetPlatformVersion>\n    <Device>{device.Udid}</Device>\n  </PropertyGroup>");
-				File.WriteAllText (proj, csproj);
+				if (!device.IsBooted)
+					Assert.That (simService.Boot (device.Udid), Is.True, $"Failed to boot simulator {device.Udid}.");
+			}
 
+			try {
 				// Replace generated tests with a single passing test
 				var testFile = Path.Combine (outputDir, "Test1.cs");
 				File.WriteAllText (testFile, $@"namespace {template};
@@ -59,21 +54,26 @@ public void TestMethod1 ()
 
 				// Run 'dotnet test' directly using Execution.RunAsync.
 				// dotnet test's MTP flow doesn't forward /p: properties to its internal
-				// ComputeRunArguments MSBuild API call, so properties must be in the csproj.
+				// ComputeRunArguments MSBuild API call, so pass properties as environment
+				// variables instead — MSBuild picks those up as global properties in the
+				// child process.
 				var env = new Dictionary<string, string?> ();
 				env ["MSBuildSDKsPath"] = null;
 				env ["MSBUILD_EXE_PATH"] = null;
+				env ["UseFloatingTargetPlatformVersion"] = "true";
+				if (device is not null)
+					env ["Device"] = device.Udid;
 				var binlog = Path.Combine (outputDir, "log-test.binlog");
 				var testArgs = new List<string> {
 					"test",
 					proj,
-					$"--device:{device.Udid}",
 					$"/bl:{binlog}"
 				};
 				var testResult = Execution.RunAsync (DotNet.Executable, testArgs, env, Console.Out, workingDirectory: outputDir, timeout: TimeSpan.FromMinutes (10)).Result;
 				Assert.That (testResult.ExitCode, Is.EqualTo (0), $"'dotnet test' failed with exit code {testResult.ExitCode}.\nBinlog: {binlog}\nOutput:\n{testResult.Output.MergedOutput}");
 			} finally {
-				simService.Shutdown (device.Udid);
+				if (device is not null)
+					simService.Shutdown (device.Udid);
 			}
 		}