diff --git a/eng/versioning.targets b/eng/versioning.targets
index 9e6d9de071847..12cad8bf7f1a6 100644
--- a/eng/versioning.targets
+++ b/eng/versioning.targets
@@ -36,11 +36,16 @@
       <CrossPlatformAndHasNoBrowserTarget>true</CrossPlatformAndHasNoBrowserTarget>
   </PropertyGroup>
   
-  <!-- Enables browser warnings for cross platform or Brwoser targeted builds -->
+  <!-- Enables browser warnings for cross platform or Browser targeted builds -->
   <ItemGroup Condition="('$(TargetsBrowser)' == 'true' or '$(CrossPlatformAndHasNoBrowserTarget)' == 'true') and '$(IsTestProject)' != 'true'">
     <SupportedPlatform Include="browser"/>
   </ItemGroup>
 
+  <!-- Enables warnings for tvOS targeted builds -->
+  <ItemGroup Condition="'$(TargetstvOS)' == 'true' and '$(IsTestProject)' != 'true'">
+    <SupportedPlatform Include="tvos"/>
+  </ItemGroup>
+  
   <ItemGroup>
     <_unsupportedOSPlatforms Include="$(UnsupportedOSPlatforms)" />
   </ItemGroup>
diff --git a/src/libraries/System.Diagnostics.Process/ref/System.Diagnostics.Process.cs b/src/libraries/System.Diagnostics.Process/ref/System.Diagnostics.Process.cs
index 599378b6ea04d..4b536fd86d54e 100644
--- a/src/libraries/System.Diagnostics.Process/ref/System.Diagnostics.Process.cs
+++ b/src/libraries/System.Diagnostics.Process/ref/System.Diagnostics.Process.cs
@@ -108,15 +108,29 @@ public static void EnterDebugMode() { }
         public static System.Diagnostics.Process[] GetProcesses(string machineName) { throw null; }
         public static System.Diagnostics.Process[] GetProcessesByName(string? processName) { throw null; }
         public static System.Diagnostics.Process[] GetProcessesByName(string? processName, string machineName) { throw null; }
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("ios")]
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("tvos")]
         public void Kill() { }
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("ios")]
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("tvos")]
         public void Kill(bool entireProcessTree) { }
         public static void LeaveDebugMode() { }
         protected void OnExited() { }
         public void Refresh() { }
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("ios")]
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("tvos")]
         public bool Start() { throw null; }
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("ios")]
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("tvos")]
         public static System.Diagnostics.Process? Start(System.Diagnostics.ProcessStartInfo startInfo) { throw null; }
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("ios")]
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("tvos")]
         public static System.Diagnostics.Process Start(string fileName) { throw null; }
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("ios")]
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("tvos")]
         public static System.Diagnostics.Process Start(string fileName, string arguments) { throw null; }
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("ios")]
+        [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("tvos")]
         public static System.Diagnostics.Process Start(string fileName, System.Collections.Generic.IEnumerable<string> arguments) { throw null; }
         [System.CLSCompliantAttribute(false)]
         [System.Runtime.Versioning.SupportedOSPlatformAttribute("windows")]
diff --git a/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.NonUap.cs b/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.NonUap.cs
index be09b7bb146ef..d2c05302f719f 100644
--- a/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.NonUap.cs
+++ b/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.NonUap.cs
@@ -3,11 +3,14 @@
 
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Runtime.Versioning;
 
 namespace System.Diagnostics
 {
     public partial class Process : IDisposable
     {
+        [UnsupportedOSPlatform("ios")]
+        [UnsupportedOSPlatform("tvos")]
         public void Kill(bool entireProcessTree)
         {
             if (!entireProcessTree)
diff --git a/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Unix.cs b/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Unix.cs
index 704fab865eb0f..05eee69f480a6 100644
--- a/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Unix.cs
+++ b/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Unix.cs
@@ -54,8 +54,15 @@ public static Process Start(string fileName, string arguments, string userName,
         }
 
         /// <summary>Terminates the associated process immediately.</summary>
+        [UnsupportedOSPlatform("ios")]
+        [UnsupportedOSPlatform("tvos")]
         public void Kill()
         {
+            if (OperatingSystem.IsIOS() || OperatingSystem.IsTvOS())
+            {
+                throw new PlatformNotSupportedException();
+            }
+
             EnsureState(State.HaveId);
 
             // Check if we know the process has exited. This avoids us targetting another
@@ -345,6 +352,11 @@ private SafeProcessHandle GetProcessHandle()
         /// <param name="startInfo">The start info with which to start the process.</param>
         private bool StartCore(ProcessStartInfo startInfo)
         {
+            if (OperatingSystem.IsIOS() || OperatingSystem.IsTvOS())
+            {
+                throw new PlatformNotSupportedException();
+            }
+
             EnsureInitialized();
 
             string? filename;
diff --git a/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Windows.cs b/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Windows.cs
index 0dfc4ae2357cb..475f31853f4d9 100644
--- a/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Windows.cs
+++ b/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Windows.cs
@@ -89,6 +89,8 @@ public static void LeaveDebugMode()
         }
 
         /// <summary>Terminates the associated process immediately.</summary>
+        [UnsupportedOSPlatform("ios")]
+        [UnsupportedOSPlatform("tvos")]
         public void Kill()
         {
             using (SafeProcessHandle handle = GetProcessHandle(Interop.Advapi32.ProcessOptions.PROCESS_TERMINATE | Interop.Advapi32.ProcessOptions.PROCESS_QUERY_LIMITED_INFORMATION, throwIfExited: false))
diff --git a/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.cs b/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.cs
index 6c9181f8655d6..1aec8ec89756f 100644
--- a/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.cs
+++ b/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.cs
@@ -2,16 +2,16 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Microsoft.Win32.SafeHandles;
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.ComponentModel;
 using System.Globalization;
 using System.IO;
 using System.Runtime.Serialization;
+using System.Runtime.Versioning;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
-using System.Runtime.Versioning;
-using System.Collections.Generic;
 
 namespace System.Diagnostics
 {
@@ -1197,6 +1197,8 @@ private void SetProcessId(int processId)
         ///       component.
         ///    </para>
         /// </devdoc>
+        [UnsupportedOSPlatform("ios")]
+        [UnsupportedOSPlatform("tvos")]
         public bool Start()
         {
             Close();
@@ -1238,6 +1240,8 @@ public bool Start()
         ///       component.
         ///    </para>
         /// </devdoc>
+        [UnsupportedOSPlatform("ios")]
+        [UnsupportedOSPlatform("tvos")]
         public static Process Start(string fileName)
         {
             // the underlying Start method can only return null on Windows platforms,
@@ -1254,6 +1258,8 @@ public static Process Start(string fileName)
         ///       component.
         ///    </para>
         /// </devdoc>
+        [UnsupportedOSPlatform("ios")]
+        [UnsupportedOSPlatform("tvos")]
         public static Process Start(string fileName, string arguments)
         {
             // the underlying Start method can only return null on Windows platforms,
@@ -1265,6 +1271,8 @@ public static Process Start(string fileName, string arguments)
         /// <summary>
         /// Starts a process resource by specifying the name of an application and a set of command line arguments
         /// </summary>
+        [UnsupportedOSPlatform("ios")]
+        [UnsupportedOSPlatform("tvos")]
         public static Process Start(string fileName, IEnumerable<string> arguments)
         {
             if (fileName == null)
@@ -1289,6 +1297,8 @@ public static Process Start(string fileName, IEnumerable<string> arguments)
         ///       component.
         ///    </para>
         /// </devdoc>
+        [UnsupportedOSPlatform("ios")]
+        [UnsupportedOSPlatform("tvos")]
         public static Process? Start(ProcessStartInfo startInfo)
         {
             Process process = new Process();