diff --git a/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/GitHubCopilotAgent.cs b/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/GitHubCopilotAgent.cs
index c966f591fc..922020b266 100644
--- a/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/GitHubCopilotAgent.cs
+++ b/dotnet/src/Microsoft.Agents.AI.GitHub.Copilot/GitHubCopilotAgent.cs
@@ -348,12 +348,12 @@ private AgentResponseUpdate ConvertToAgentResponseUpdate(AssistantMessageDeltaEv
 
     private AgentResponseUpdate ConvertToAgentResponseUpdate(AssistantMessageEvent assistantMessage)
     {
-        TextContent textContent = new(assistantMessage.Data?.Content ?? string.Empty)
+        AIContent content = new()
         {
             RawRepresentation = assistantMessage
         };
 
-        return new AgentResponseUpdate(ChatRole.Assistant, [textContent])
+        return new AgentResponseUpdate(ChatRole.Assistant, [content])
         {
             AgentId = this.Id,
             ResponseId = assistantMessage.Data?.MessageId,
diff --git a/dotnet/tests/Microsoft.Agents.AI.GitHub.Copilot.UnitTests/GitHubCopilotAgentTests.cs b/dotnet/tests/Microsoft.Agents.AI.GitHub.Copilot.UnitTests/GitHubCopilotAgentTests.cs
index 8a4d3c1068..dfd6a629cc 100644
--- a/dotnet/tests/Microsoft.Agents.AI.GitHub.Copilot.UnitTests/GitHubCopilotAgentTests.cs
+++ b/dotnet/tests/Microsoft.Agents.AI.GitHub.Copilot.UnitTests/GitHubCopilotAgentTests.cs
@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Reflection;
 using System.Threading.Tasks;
 using GitHub.Copilot.SDK;
 using Microsoft.Extensions.AI;
@@ -221,4 +222,33 @@ public void CopyResumeSessionConfig_WithNullSource_ReturnsDefaults()
         Assert.Null(result.ConfigDir);
         Assert.True(result.Streaming);
     }
+
+    [Fact]
+    public void ConvertToAgentResponseUpdate_AssistantMessageEvent_DoesNotEmitTextContent()
+    {
+        var assistantMessage = new AssistantMessageEvent
+        {
+            Data = new AssistantMessageData
+            {
+                MessageId = "msg-456",
+                Content = "Some streamed content that was already delivered via delta events"
+            }
+        };
+        CopilotClient copilotClient = new(new CopilotClientOptions { AutoStart = false });
+        const string TestId = "agent-id";
+        var agent = new GitHubCopilotAgent(copilotClient, ownsClient: false, id: TestId, tools: null);
+        MethodInfo method = typeof(GitHubCopilotAgent).GetMethod(
+            "ConvertToAgentResponseUpdate",
+            BindingFlags.NonPublic | BindingFlags.Instance,
+            binder: null,
+            types: [typeof(AssistantMessageEvent)],
+            modifiers: null)!;
+
+        var result = (AgentResponseUpdate)method.Invoke(agent, [assistantMessage])!;
+
+        // result.Text need to be empty because the content was already delivered via delta events, and we want to avoid emitting duplicate content in the response update.
+        // The content should be delivered through TextContent in the Contents collection instead.
+        Assert.Empty(result.Text);
+        Assert.DoesNotContain(result.Contents, c => c is TextContent);
+    }
 }