diff --git a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/ref/System.Runtime.InteropServices.RuntimeInformation.cs b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/ref/System.Runtime.InteropServices.RuntimeInformation.cs
index e9c675b61f2e89..46d2dd5159e22f 100644
--- a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/ref/System.Runtime.InteropServices.RuntimeInformation.cs
+++ b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/ref/System.Runtime.InteropServices.RuntimeInformation.cs
@@ -23,6 +23,8 @@ public enum Architecture
         public static System.Runtime.InteropServices.OSPlatform FreeBSD { get { throw null; } }
         public static System.Runtime.InteropServices.OSPlatform iOS { get { throw null; } }
         public static System.Runtime.InteropServices.OSPlatform Linux { get { throw null; } }
+        public static System.Runtime.InteropServices.OSPlatform macOS { get { throw null; } }
+        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
         public static System.Runtime.InteropServices.OSPlatform OSX { get { throw null; } }
         public static System.Runtime.InteropServices.OSPlatform tvOS { get { throw null; } }
         public static System.Runtime.InteropServices.OSPlatform watchOS { get { throw null; } }
diff --git a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/OSPlatform.cs b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/OSPlatform.cs
index 39f956e164bd03..18e45643d216f4 100644
--- a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/OSPlatform.cs
+++ b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/OSPlatform.cs
@@ -15,6 +15,9 @@ namespace System.Runtime.InteropServices
 
         public static OSPlatform Linux { get; } = new OSPlatform("LINUX");
 
+        public static OSPlatform macOS { get; } = new OSPlatform("MACOS");
+
+        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)] // superseded by macOS
         public static OSPlatform OSX { get; } = new OSPlatform("OSX");
 
         public static OSPlatform iOS { get; } = new OSPlatform("IOS");
@@ -25,14 +28,21 @@ namespace System.Runtime.InteropServices
 
         public static OSPlatform Windows { get; } = new OSPlatform("WINDOWS");
 
+        internal bool IsCurrent { get; } // this information is cached because it's frequently used
+
         private OSPlatform(string osPlatform)
         {
             if (osPlatform == null) throw new ArgumentNullException(nameof(osPlatform));
             if (osPlatform.Length == 0) throw new ArgumentException(SR.Argument_EmptyValue, nameof(osPlatform));
 
             _osPlatform = osPlatform;
+            IsCurrent = RuntimeInformation.IsCurrentOSPlatform(osPlatform);
         }
 
+        /// <summary>
+        /// Creates a new OSPlatform instance.
+        /// </summary>
+        /// <remarks>If you plan to call this method frequently, please consider caching its result.</remarks>
         public static OSPlatform Create(string osPlatform)
         {
             return new OSPlatform(osPlatform);
@@ -45,17 +55,17 @@ public bool Equals(OSPlatform other)
 
         internal bool Equals(string? other)
         {
-            return string.Equals(_osPlatform, other, StringComparison.Ordinal);
+            return string.Equals(_osPlatform, other, StringComparison.OrdinalIgnoreCase);
         }
 
         public override bool Equals(object? obj)
         {
-            return obj is OSPlatform && Equals((OSPlatform)obj);
+            return obj is OSPlatform osPlatform && Equals(osPlatform);
         }
 
         public override int GetHashCode()
         {
-            return _osPlatform == null ? 0 : _osPlatform.GetHashCode();
+            return _osPlatform == null ? 0 : _osPlatform.GetHashCode(StringComparison.OrdinalIgnoreCase);
         }
 
         public override string ToString()
diff --git a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Browser.cs b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Browser.cs
index 769d4ae38f30f9..838aa49c2e76ec 100644
--- a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Browser.cs
+++ b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Browser.cs
@@ -5,7 +5,7 @@ namespace System.Runtime.InteropServices
 {
     public static partial class RuntimeInformation
     {
-        public static bool IsOSPlatform(OSPlatform osPlatform) => osPlatform.Equals(OSPlatform.Browser);
+        internal static bool IsCurrentOSPlatform(string osPlatform) => osPlatform.Equals("BROWSER", StringComparison.OrdinalIgnoreCase);
 
         public static string OSDescription => "Browser";
 
diff --git a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Unix.cs b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Unix.cs
index c930aac9254063..ea7db57e016f81 100644
--- a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Unix.cs
+++ b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Unix.cs
@@ -14,10 +14,12 @@ public static partial class RuntimeInformation
         private static Architecture? s_osArch;
         private static Architecture? s_processArch;
 
-        public static bool IsOSPlatform(OSPlatform osPlatform)
+        internal static bool IsCurrentOSPlatform(string osPlatform)
         {
             string name = s_osPlatformName ??= Interop.Sys.GetUnixName();
-            return osPlatform.Equals(name);
+
+            return osPlatform.Equals(name, StringComparison.OrdinalIgnoreCase)
+                || (name == "OSX" && osPlatform.Equals("MACOS", StringComparison.OrdinalIgnoreCase)); // GetUnixName returns OSX on macOS
         }
 
         public static string OSDescription => s_osDescription ??= Interop.Sys.GetUnixVersion();
diff --git a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Windows.cs b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Windows.cs
index 0ccc9deb930047..7c71cc972aad5d 100644
--- a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Windows.cs
+++ b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.Windows.cs
@@ -13,10 +13,7 @@ public static partial class RuntimeInformation
         private static Architecture? s_osArch;
         private static Architecture? s_processArch;
 
-        public static bool IsOSPlatform(OSPlatform osPlatform)
-        {
-            return OSPlatform.Windows == osPlatform;
-        }
+        internal static bool IsCurrentOSPlatform(string osPlatform) => osPlatform.Equals("WINDOWS", StringComparison.OrdinalIgnoreCase);
 
         public static string OSDescription
         {
diff --git a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.cs b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.cs
index 8e43d13ec46389..95b1b62b4cdbe7 100644
--- a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.cs
+++ b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.cs
@@ -48,5 +48,10 @@ public static string FrameworkDescription
         /// </remarks>
         public static string RuntimeIdentifier =>
             s_runtimeIdentifier ??= AppContext.GetData("RUNTIME_IDENTIFIER") as string ?? "unknown";
+
+        /// <summary>
+        /// Indicates whether the current application is running on the specified platform.
+        /// </summary>
+        public static bool IsOSPlatform(OSPlatform osPlatform) => osPlatform.IsCurrent;
     }
 }
diff --git a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/tests/CheckPlatformTests.cs b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/tests/CheckPlatformTests.cs
index 1264c5c0d850ad..e40f9f8b310afe 100644
--- a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/tests/CheckPlatformTests.cs
+++ b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/tests/CheckPlatformTests.cs
@@ -1,7 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.Runtime.InteropServices;
 using Xunit;
 
 namespace System.Runtime.InteropServices.RuntimeInformationTests
@@ -13,10 +12,10 @@ public void CheckLinux()
         {
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Linux));
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("LINUX")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("linux")));
 
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("DARWIN")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("FREEBSD")));
-            Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("linux")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NETBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NetBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("netbsd")));
@@ -31,9 +30,9 @@ public void CheckLinux()
         public void CheckNetBSD()
         {
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NETBSD")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NetBSD")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("netbsd")));
 
-            Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NetBSD")));
-            Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("netbsd")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("DARWIN")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("FREEBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("LINUX")));
@@ -51,12 +50,16 @@ public void CheckOSX()
         {
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.OSX));
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("OSX")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("osx")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.macOS));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("MACOS")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("macOS")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("macos")));
 
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("FREEBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NETBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NetBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("netbsd")));
-            Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("osx")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("mac")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("DARWIN")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("MACOSX")));
@@ -70,6 +73,8 @@ public void CheckiOS()
         {
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.iOS));
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("IOS")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("iOS")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("ios")));
 
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("FREEBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NETBSD")));
@@ -89,6 +94,8 @@ public void ChecktvOS()
         {
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.tvOS));
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("TVOS")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("tvOS")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("tvos")));
 
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("FREEBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NETBSD")));
@@ -108,6 +115,7 @@ public void CheckAndroid()
         {
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Android));
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("ANDROID")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("android")));
 
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("FREEBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NETBSD")));
@@ -127,6 +135,7 @@ public void CheckBrowser()
         {
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Browser));
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("BROWSER")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("browser")));
 
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("FREEBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NETBSD")));
@@ -146,13 +155,14 @@ public void CheckWindows()
         {
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Windows));
             Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("WINDOWS")));
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Create("windows")));
 
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("FREEBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NETBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("NetBSD")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("netbsd")));
-            Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("windows")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("Windows NT")));
+            Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Create("win")));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.Linux));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.OSX));
             Assert.False(RuntimeInformation.IsOSPlatform(OSPlatform.FreeBSD));
@@ -213,5 +223,17 @@ public void CheckOSPlatform()
             Assert.Equal(0, defaultObj.GetHashCode());
             Assert.Equal(defaultObj.GetHashCode(), conObj.GetHashCode());
         }
+
+        [Fact]
+        public void StringComparisonOrdinalIgnoreCaseIsUsed()
+        {
+            Assert.Equal(OSPlatform.Create("A"), OSPlatform.Create("a"));
+            Assert.Equal(OSPlatform.Create("A"), OSPlatform.Create("A"));
+            Assert.Equal(OSPlatform.Create("a"), OSPlatform.Create("a"));
+
+            Assert.Equal(OSPlatform.Create("A").GetHashCode(), OSPlatform.Create("a").GetHashCode());
+            Assert.Equal(OSPlatform.Create("A").GetHashCode(), OSPlatform.Create("A").GetHashCode());
+            Assert.Equal(OSPlatform.Create("a").GetHashCode(), OSPlatform.Create("a").GetHashCode());
+        }
     }
 }
diff --git a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/tests/PlatformVersionTests.cs b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/tests/PlatformVersionTests.cs
index c00ace31490338..b612d2e065bcba 100644
--- a/src/libraries/System.Runtime.InteropServices.RuntimeInformation/tests/PlatformVersionTests.cs
+++ b/src/libraries/System.Runtime.InteropServices.RuntimeInformation/tests/PlatformVersionTests.cs
@@ -14,6 +14,11 @@ public static IEnumerable<object[]> AllKnownOsPlatforms()
             yield return new object[] { OSPlatform.Linux };
             yield return new object[] { OSPlatform.OSX };
             yield return new object[] { OSPlatform.Browser };
+            yield return new object[] { OSPlatform.macOS };
+            yield return new object[] { OSPlatform.iOS };
+            yield return new object[] { OSPlatform.tvOS };
+            yield return new object[] { OSPlatform.watchOS };
+            yield return new object[] { OSPlatform.Android };
         }
 
         [Fact]
@@ -49,6 +54,8 @@ public void IsOSPlatformOrLater_ReturnsTrue_ForCurrentOS(OSPlatform osPlatform)
             Version current = Environment.OSVersion.Version;
 
             Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformOrLater($"{osPlatform}{current}"));
+            Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformOrLater($"{osPlatform.ToString().ToLower()}{current}"));
+            Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformOrLater($"{osPlatform.ToString().ToUpper()}{current}"));
 
             Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformOrLater(osPlatform, current.Major));
 
@@ -78,6 +85,8 @@ public void IsOSPlatformOrLater_ReturnsFalse_ForNewerVersionOfCurrentOS(OSPlatfo
 
             Version newer = new Version(currentVersion.Major + 1, 0);
             Assert.False(RuntimeInformation.IsOSPlatformOrLater($"{osPlatform}{newer}"));
+            Assert.False(RuntimeInformation.IsOSPlatformOrLater($"{osPlatform.ToString().ToLower()}{newer}"));
+            Assert.False(RuntimeInformation.IsOSPlatformOrLater($"{osPlatform.ToString().ToUpper()}{newer}"));
             Assert.False(RuntimeInformation.IsOSPlatformOrLater(osPlatform, newer.Major));
 
             newer = new Version(currentVersion.Major, currentVersion.Minor + 1);
@@ -104,6 +113,8 @@ public void IsOSPlatformOrLater_ReturnsTrue_ForOlderVersionOfCurrentOS(OSPlatfor
 
             Version older = new Version(current.Major - 1, 0);
             Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformOrLater($"{osPlatform}{older}"));
+            Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformOrLater($"{osPlatform.ToString().ToLower()}{older}"));
+            Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformOrLater($"{osPlatform.ToString().ToUpper()}{older}"));
             Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformOrLater(osPlatform, older.Major));
 
             if (current.Minor > 0)
@@ -160,6 +171,8 @@ public void IsOSPlatformEarlierThan_ReturnsFalse_ForCurrentOS(OSPlatform osPlatf
             Version current = Environment.OSVersion.Version;
 
             Assert.False(RuntimeInformation.IsOSPlatformEarlierThan($"{osPlatform}{current}"));
+            Assert.False(RuntimeInformation.IsOSPlatformEarlierThan($"{osPlatform.ToString().ToLower()}{current}"));
+            Assert.False(RuntimeInformation.IsOSPlatformEarlierThan($"{osPlatform.ToString().ToUpper()}{current}"));
 
             Assert.False(RuntimeInformation.IsOSPlatformEarlierThan(osPlatform, current.Major));
 
@@ -190,6 +203,8 @@ public void IsOSPlatformEarlierThan_ReturnsTrue_ForNewerVersionOfCurrentOS(OSPla
 
             Version newer = new Version(current.Major + 1, 0);
             Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformEarlierThan($"{osPlatform}{newer}"));
+            Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformEarlierThan($"{osPlatform.ToString().ToLower()}{newer}"));
+            Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformEarlierThan($"{osPlatform.ToString().ToUpper()}{newer}"));
             Assert.Equal(isCurrentPlatfom, RuntimeInformation.IsOSPlatformEarlierThan(osPlatform, newer.Major));
 
             newer = new Version(current.Major, current.Minor + 1);
@@ -215,6 +230,8 @@ public void IsOSPlatformEarlierThan_ReturnsFalse_ForOlderVersionOfCurrentOS(OSPl
 
             Version older = new Version(current.Major - 1, 0);
             Assert.False(RuntimeInformation.IsOSPlatformEarlierThan($"{osPlatform}{older}"));
+            Assert.False(RuntimeInformation.IsOSPlatformEarlierThan($"{osPlatform.ToString().ToLower()}{older}"));
+            Assert.False(RuntimeInformation.IsOSPlatformEarlierThan($"{osPlatform.ToString().ToUpper()}{older}"));
             Assert.False(RuntimeInformation.IsOSPlatformEarlierThan(osPlatform, older.Major));
 
             if (current.Minor > 0)