diff --git a/src/libraries/System.Net.Security/src/Resources/Strings.resx b/src/libraries/System.Net.Security/src/Resources/Strings.resx
index 8af05ebe134c8d..1270f6bb3be83a 100644
--- a/src/libraries/System.Net.Security/src/Resources/Strings.resx
+++ b/src/libraries/System.Net.Security/src/Resources/Strings.resx
@@ -443,4 +443,7 @@
   <data name="net_ssl_ciphersuites_policy_not_supported" xml:space="preserve">
     <value>CipherSuitesPolicy is not supported on this platform.</value>
   </data>
+  <data name="SystemNetSecurity_PlatformNotSupported" xml:space="preserve">
+    <value>System.Net.Security is not supported on this platform.</value>
+  </data>
 </root>
diff --git a/src/libraries/System.Net.Security/src/System.Net.Security.csproj b/src/libraries/System.Net.Security/src/System.Net.Security.csproj
index 30737df95bbcca..cce9afa62bc968 100644
--- a/src/libraries/System.Net.Security/src/System.Net.Security.csproj
+++ b/src/libraries/System.Net.Security/src/System.Net.Security.csproj
@@ -7,10 +7,13 @@
     <DefineConstants>$(DefineConstants);PRODUCT</DefineConstants>
     <Nullable>enable</Nullable>
   </PropertyGroup>
+  <PropertyGroup>
+    <GeneratePlatformNotSupportedAssemblyMessage Condition="'$(TargetsBrowser)' == 'true'">SR.SystemNetSecurity_PlatformNotSupported</GeneratePlatformNotSupportedAssemblyMessage>
+  </PropertyGroup>
   <PropertyGroup Condition="'$(TargetsOSX)' == 'true' or '$(TargetsiOS)' == 'true' or '$(TargetstvOS)' == 'true'">
     <DefineConstants>$(DefineConstants);SYSNETSECURITY_NO_OPENSSL</DefineConstants>
   </PropertyGroup>
-  <ItemGroup>
+  <ItemGroup Condition="'$(TargetsBrowser)' != 'true'">
     <Compile Include="System\Net\CertificateValidationPal.cs" />
     <Compile Include="System\Net\Logging\NetEventSource.cs" />
     <Compile Include="System\Net\SslStreamContext.cs" />
@@ -86,7 +89,7 @@
   <!-- This file depends on IANA registry. We do not want anyone's build to break after the update -->
   <!-- or if they don't have internet connection - explicit opt-in required -->
   <!-- To expose newly generated APIs, generated file have to be deliberately copied -->
-  <ItemGroup>
+  <ItemGroup Condition="'$(TargetsBrowser)' != 'true'">
     <Compile Include="System\Net\Security\TlsCipherSuite.cs">
       <DesignTime>True</DesignTime>
       <AutoGen>True</AutoGen>
@@ -94,7 +97,7 @@
     </Compile>
     <None Include="System\Net\Security\TlsCipherSuiteNameParser.ttinclude" />
   </ItemGroup>
-  <ItemGroup Condition=" '$(TargetsUnix)' == 'true' or '$(TargetsBrowser)' == 'true' ">
+  <ItemGroup Condition="'$(TargetsUnix)' == 'true'">
     <Compile Include="System\Net\Security\TlsCipherSuiteData.Lookup.cs">
       <DesignTime>True</DesignTime>
       <AutoGen>True</AutoGen>
@@ -206,7 +209,7 @@
     <Compile Include="$(CommonPath)Interop\Windows\SspiCli\SecPkgContext_StreamSizes.cs"
              Link="Common\Interop\Windows\SspiCli\SecPkgContext_StreamSizes.cs" />
   </ItemGroup>
-  <ItemGroup Condition=" '$(TargetsUnix)' == 'true' or '$(TargetsBrowser)' == 'true' ">
+  <ItemGroup Condition="'$(TargetsUnix)' == 'true'">
     <Compile Include="$(CommonPath)Interop\Unix\Interop.Libraries.cs"
              Link="Common\Interop\Unix\Interop.Libraries.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\Interop.Errors.cs"
@@ -245,7 +248,7 @@
     <Compile Include="System\Net\Security\SslConnectionInfo.Unix.cs" />
     <Compile Include="System\Net\Security\TlsCipherSuiteData.cs" />
   </ItemGroup>
-  <ItemGroup Condition="('$(TargetsUnix)' == 'true' or '$(TargetsBrowser)' == 'true') and '$(TargetsOSX)' != 'true' and '$(TargetsiOS)' != 'true' and '$(TargetstvOS)' != 'true'">
+  <ItemGroup Condition="'$(TargetsUnix)' == 'true' and '$(TargetsOSX)' != 'true' and '$(TargetsiOS)' != 'true' and '$(TargetstvOS)' != 'true'">
     <Compile Include="System\Net\CertificateValidationPal.Unix.cs" />
     <Compile Include="System\Net\Security\CipherSuitesPolicyPal.Linux.cs" />
     <Compile Include="System\Net\Security\SslStreamPal.Unix.cs" />
@@ -358,7 +361,7 @@
     <Reference Include="System.Threading" />
     <Reference Include="System.Threading.ThreadPool" />
   </ItemGroup>
-  <ItemGroup Condition="'$(TargetsUnix)' == 'true' or '$(TargetsBrowser)' == 'true'">
+  <ItemGroup Condition="'$(TargetsUnix)' == 'true'">
     <Reference Include="System.Console" Condition="'$(Configuration)' == 'Debug'" />
     <Reference Include="System.Diagnostics.StackTrace" />
     <Reference Include="System.Security.Cryptography.Algorithms" />
diff --git a/src/libraries/System.Net.Security/tests/FunctionalTests/AssemblyInfo.cs b/src/libraries/System.Net.Security/tests/FunctionalTests/AssemblyInfo.cs
index 54c8a4d926e5c3..4b859917fd8cb2 100644
--- a/src/libraries/System.Net.Security/tests/FunctionalTests/AssemblyInfo.cs
+++ b/src/libraries/System.Net.Security/tests/FunctionalTests/AssemblyInfo.cs
@@ -4,3 +4,4 @@
 using Xunit;
 
 [assembly: ActiveIssue("https://github.com/dotnet/runtime/issues/34690", TestPlatforms.Windows, TargetFrameworkMonikers.Netcoreapp, TestRuntimes.Mono)]
+[assembly: SkipOnMono("System.Net.Security is not supported on Browser", TestPlatforms.Browser)]
\ No newline at end of file
diff --git a/src/libraries/System.Net.Security/tests/FunctionalTests/System.Net.Security.Tests.csproj b/src/libraries/System.Net.Security/tests/FunctionalTests/System.Net.Security.Tests.csproj
index a1e3f33b84be1c..3845b272ae6aed 100644
--- a/src/libraries/System.Net.Security/tests/FunctionalTests/System.Net.Security.Tests.csproj
+++ b/src/libraries/System.Net.Security/tests/FunctionalTests/System.Net.Security.Tests.csproj
@@ -4,9 +4,12 @@
     <AllowUnsafeBlocks Condition="'$(TargetsUnix)' == 'true' or '$(TargetsBrowser)' == 'true'">true</AllowUnsafeBlocks>
     <TargetFrameworks>$(NetCoreAppCurrent)-Windows_NT;$(NetCoreAppCurrent)-Unix;$(NetCoreAppCurrent)-Browser;$(NetCoreAppCurrent)-OSX;$(NetCoreAppCurrent)-iOS</TargetFrameworks>
     <Nullable>annotations</Nullable>
+    <IgnoreForCI Condition="'$(TargetOS)' == 'Browser'">true</IgnoreForCI>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="AssemblyInfo.cs" />
+  </ItemGroup>
+  <ItemGroup Condition="'$(TargetsBrowser)' != 'true'">
     <Compile Include="NotifyReadVirtualNetworkStream.cs" />
     <Compile Include="DummyTcpServer.cs" />
     <Compile Include="SslStreamExtensions.cs" />
@@ -84,7 +87,7 @@
     <Compile Include="SslStreamCredentialCacheTest.cs" />
     <Compile Include="SslStreamSystemDefaultsTest.cs" />
   </ItemGroup>
-  <ItemGroup>
+  <ItemGroup Condition="'$(TargetsBrowser)' != 'true'">
     <Compile Include="LoggingTest.cs" />
     <Compile Include="$(CommonTestPath)System\Diagnostics\Tracing\TestEventListener.cs"
              Link="Common\System\Diagnostics\Tracing\TestEventListener.cs" />
@@ -94,7 +97,7 @@
     <Compile Include="$(CommonTestPath)System\Net\Capability.Security.Windows.cs"
              Link="Common\System\Net\Capability.Security.Windows.cs" />
   </ItemGroup>
-  <ItemGroup Condition="'$(TargetsUnix)' == 'true' or '$(TargetsBrowser)' == 'true'">
+  <ItemGroup Condition="'$(TargetsUnix)' == 'true'">
     <Compile Include="IdentityValidator.Unix.cs" />
     <Compile Include="$(CommonTestPath)System\Net\Capability.Security.Unix.cs"
              Link="Common\System\Net\Capability.Security.Unix.cs" />
diff --git a/src/libraries/System.Net.Security/tests/UnitTests/AssemblyInfo.cs b/src/libraries/System.Net.Security/tests/UnitTests/AssemblyInfo.cs
new file mode 100644
index 00000000000000..766d39919ff4eb
--- /dev/null
+++ b/src/libraries/System.Net.Security/tests/UnitTests/AssemblyInfo.cs
@@ -0,0 +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 Xunit;
+
+[assembly: SkipOnMono("System.Net.Security is not supported on Browser", TestPlatforms.Browser)]
\ No newline at end of file
diff --git a/src/libraries/System.Net.Security/tests/UnitTests/System.Net.Security.Unit.Tests.csproj b/src/libraries/System.Net.Security/tests/UnitTests/System.Net.Security.Unit.Tests.csproj
index 2323a9323b51b3..8379fd48c4792a 100644
--- a/src/libraries/System.Net.Security/tests/UnitTests/System.Net.Security.Unit.Tests.csproj
+++ b/src/libraries/System.Net.Security/tests/UnitTests/System.Net.Security.Unit.Tests.csproj
@@ -12,8 +12,12 @@
     <NoWarn>$(NoWarn);3021</NoWarn>
     <TargetFrameworks>$(NetCoreAppCurrent)-Windows_NT;$(NetCoreAppCurrent)-Unix;$(NetCoreAppCurrent)-Browser;$(NetCoreAppCurrent)-OSX;$(NetCoreAppCurrent)-iOS</TargetFrameworks>
     <Nullable>annotations</Nullable>
+    <IgnoreForCI Condition="'$(TargetOS)' == 'Browser'">true</IgnoreForCI>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="AssemblyInfo.cs" />
+  </ItemGroup>
+  <ItemGroup Condition="'$(TargetsBrowser)' != 'true'">
     <Compile Include="SslApplicationProtocolTests.cs" />
     <Compile Include="SslAuthenticationOptionsTests.cs" />
     <Compile Include="SslStreamAllowedProtocolsTest.cs" />
@@ -30,7 +34,7 @@
     <Compile Include="$(CommonPath)System\HexConverter.cs"
              Link="Common\System\HexConverter.cs" />
   </ItemGroup>
-  <ItemGroup>
+  <ItemGroup Condition="'$(TargetsBrowser)' != 'true'">
     <!-- Production code references -->
     <Compile Include="..\..\src\System\Net\Security\NetEventSource.Security.cs"
              Link="ProductionCode\System\Net\Security\NetEventSource.Security.cs" />
diff --git a/src/libraries/tests.proj b/src/libraries/tests.proj
index 4a8efb0e136bc6..f4ffdf695e6356 100644
--- a/src/libraries/tests.proj
+++ b/src/libraries/tests.proj
@@ -39,7 +39,6 @@
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Net.Http\tests\FunctionalTests\System.Net.Http.Functional.Tests.csproj" />
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Net.Primitives\tests\FunctionalTests\System.Net.Primitives.Functional.Tests.csproj" />
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Net.Primitives\tests\PalTests\System.Net.Primitives.Pal.Tests.csproj" />
-    <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Net.Security\tests\FunctionalTests\System.Net.Security.Tests.csproj" />
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Net.WebSockets.Client\tests\System.Net.WebSockets.Client.Tests.csproj" />
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.ObjectModel\tests\System.ObjectModel.Tests.csproj" />
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Private.Uri\tests\FunctionalTests\System.Private.Uri.Functional.Tests.csproj" />