diff --git a/dotnet/src/webdriver/BiDi/BrowsingContext/CaptureScreenshotCommand.cs b/dotnet/src/webdriver/BiDi/BrowsingContext/CaptureScreenshotCommand.cs
index 4bb970bf50ea8..8fd178f1655d5 100644
--- a/dotnet/src/webdriver/BiDi/BrowsingContext/CaptureScreenshotCommand.cs
+++ b/dotnet/src/webdriver/BiDi/BrowsingContext/CaptureScreenshotCommand.cs
@@ -18,6 +18,7 @@
 // </copyright>
 
 using OpenQA.Selenium.BiDi.Communication;
+using System;
 using System.Text.Json.Serialization;
 
 namespace OpenQA.Selenium.BiDi.BrowsingContext;
@@ -56,9 +57,9 @@ public sealed record BoxClipRectangle(double X, double Y, double Width, double H
 
 public sealed record ElementClipRectangle(Script.ISharedReference Element) : ClipRectangle;
 
-public sealed record CaptureScreenshotResult(string Data) : EmptyResult
+public sealed record CaptureScreenshotResult(ReadOnlyMemory<byte> Data) : EmptyResult
 {
     public static implicit operator byte[](CaptureScreenshotResult captureScreenshotResult) => captureScreenshotResult.ToByteArray();
 
-    public byte[] ToByteArray() => System.Convert.FromBase64String(Data);
+    public byte[] ToByteArray() => Data.ToArray();
 }
diff --git a/dotnet/src/webdriver/BiDi/BrowsingContext/PrintCommand.cs b/dotnet/src/webdriver/BiDi/BrowsingContext/PrintCommand.cs
index d9180f9ecc59b..710069ee9e163 100644
--- a/dotnet/src/webdriver/BiDi/BrowsingContext/PrintCommand.cs
+++ b/dotnet/src/webdriver/BiDi/BrowsingContext/PrintCommand.cs
@@ -112,7 +112,7 @@ public static implicit operator PrintPageRange(Range range)
 #endif
 }
 
-public sealed record PrintResult(string Data) : EmptyResult
+public sealed record PrintResult(ReadOnlyMemory<byte> Data) : EmptyResult
 {
-    public byte[] ToByteArray() => Convert.FromBase64String(Data);
+    public byte[] ToByteArray() => Data.ToArray();
 }
diff --git a/dotnet/src/webdriver/BiDi/Network/BytesValue.cs b/dotnet/src/webdriver/BiDi/Network/BytesValue.cs
index 9952bff13f1c2..8d57fb7b52f0f 100644
--- a/dotnet/src/webdriver/BiDi/Network/BytesValue.cs
+++ b/dotnet/src/webdriver/BiDi/Network/BytesValue.cs
@@ -28,9 +28,9 @@ namespace OpenQA.Selenium.BiDi.Network;
 public abstract record BytesValue
 {
     public static implicit operator BytesValue(string value) => new StringBytesValue(value);
-    public static implicit operator BytesValue(byte[] value) => new Base64BytesValue(Convert.ToBase64String(value));
+    public static implicit operator BytesValue(byte[] value) => new Base64BytesValue(value);
 }
 
 public sealed record StringBytesValue(string Value) : BytesValue;
 
-public sealed record Base64BytesValue(string Value) : BytesValue;
+public sealed record Base64BytesValue(ReadOnlyMemory<byte> Value) : BytesValue;
diff --git a/dotnet/src/webdriver/BiDi/WebExtension/InstallCommand.cs b/dotnet/src/webdriver/BiDi/WebExtension/InstallCommand.cs
index 4092203c47bac..8027787d72eec 100644
--- a/dotnet/src/webdriver/BiDi/WebExtension/InstallCommand.cs
+++ b/dotnet/src/webdriver/BiDi/WebExtension/InstallCommand.cs
@@ -18,6 +18,7 @@
 // </copyright>
 
 using OpenQA.Selenium.BiDi.Communication;
+using System;
 using System.Text.Json.Serialization;
 
 namespace OpenQA.Selenium.BiDi.WebExtension;
@@ -35,7 +36,7 @@ public abstract record ExtensionData;
 
 public sealed record ExtensionArchivePath(string Path) : ExtensionData;
 
-public sealed record ExtensionBase64Encoded(string Value) : ExtensionData;
+public sealed record ExtensionBase64Encoded(ReadOnlyMemory<byte> Value) : ExtensionData;
 
 public sealed record ExtensionPath(string Path) : ExtensionData;
 
diff --git a/dotnet/test/common/BiDi/BrowsingContext/BrowsingContextTest.cs b/dotnet/test/common/BiDi/BrowsingContext/BrowsingContextTest.cs
index 1ee5cf6216c63..ed10187f7e045 100644
--- a/dotnet/test/common/BiDi/BrowsingContext/BrowsingContextTest.cs
+++ b/dotnet/test/common/BiDi/BrowsingContext/BrowsingContextTest.cs
@@ -250,7 +250,7 @@ public async Task CanCaptureScreenshot()
         var screenshot = await context.CaptureScreenshotAsync();
 
         Assert.That(screenshot, Is.Not.Null);
-        Assert.That(screenshot.Data, Is.Not.Empty);
+        Assert.That(screenshot.Data.Length, Is.Not.Zero);
     }
 
     [Test]
@@ -263,7 +263,7 @@ public async Task CanCaptureScreenshotWithParameters()
         });
 
         Assert.That(screenshot, Is.Not.Null);
-        Assert.That(screenshot.Data, Is.Not.Empty);
+        Assert.That(screenshot.Data.Length, Is.Not.Zero);
     }
 
     [Test]
@@ -276,7 +276,7 @@ public async Task CanCaptureScreenshotOfViewport()
         });
 
         Assert.That(screenshot, Is.Not.Null);
-        Assert.That(screenshot.Data, Is.Not.Empty);
+        Assert.That(screenshot.Data.Length, Is.Not.Zero);
     }
 
     [Test]
@@ -292,7 +292,7 @@ public async Task CanCaptureScreenshotOfElement()
         });
 
         Assert.That(screenshot, Is.Not.Null);
-        Assert.That(screenshot.Data, Is.Not.Empty);
+        Assert.That(screenshot.Data.Length, Is.Not.Zero);
     }
 
     [Test]
@@ -313,6 +313,6 @@ public async Task CanPrintPage()
         var pdf = await context.PrintAsync();
 
         Assert.That(pdf, Is.Not.Null);
-        Assert.That(pdf.Data, Is.Not.Empty);
+        Assert.That(pdf.Data.Length, Is.Not.Zero);
     }
 }
diff --git a/dotnet/test/common/BiDi/WebExtension/WebExtensionTest.cs b/dotnet/test/common/BiDi/WebExtension/WebExtensionTest.cs
index 4be01281dc79c..327ce5d4d29f3 100644
--- a/dotnet/test/common/BiDi/WebExtension/WebExtensionTest.cs
+++ b/dotnet/test/common/BiDi/WebExtension/WebExtensionTest.cs
@@ -64,9 +64,9 @@ public async Task CanInstallBase64WebExtension()
     {
         var path = LocateRelativePath("common/extensions/webextensions-selenium-example.zip");
 
-        string base64 = Convert.ToBase64String(File.ReadAllBytes(path));
+        var bytes = File.ReadAllBytes(path);
 
-        var result = await bidi.WebExtension.InstallAsync(new ExtensionBase64Encoded(base64));
+        var result = await bidi.WebExtension.InstallAsync(new ExtensionBase64Encoded(bytes));
 
         Assert.That(result, Is.Not.Null);
         Assert.That(result.Extension, Is.Not.Null);