diff --git a/CHANGELOG.md b/CHANGELOG.md
index ed975f4a1fa..28ea1b369a8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1 +1,2 @@
+- Moved MCP server `firebase-debug.log` to `~/.cache/firebase/firebase-debug.log`. (#9982)
 - Added a prompt to `firebase init` to install Agent Skills for Firebase.
diff --git a/src/bin/mcp.ts b/src/bin/mcp.ts
index ff48e8cea31..448c5df3cef 100644
--- a/src/bin/mcp.ts
+++ b/src/bin/mcp.ts
@@ -1,6 +1,8 @@
 #!/usr/bin/env node
 
-import { resolve } from "path";
+import { resolve, join } from "path";
+import { mkdir } from "fs/promises";
+import { homedir } from "os";
 import { parseArgs } from "util";
 import { useFileLogger } from "../logger";
 import { FirebaseMcpServer } from "../mcp/index";
@@ -84,7 +86,10 @@ export async function mcp(): Promise<void> {
   if (earlyExit) return;
 
   setFirebaseMcp(true);
-  useFileLogger();
+  // Write debug logs to ~/.cache/firebase to avoid polluting the user's project directory.
+  const mcpLogDir = join(homedir(), ".cache", "firebase");
+  await mkdir(mcpLogDir, { recursive: true });
+  useFileLogger(join(mcpLogDir, "firebase-debug.log"));
   const activeFeatures = (values.only || "")
     .split(",")
     .map((f) => f.trim())