diff --git a/packages/cli/src/tts/synthesize.cache.test.ts b/packages/cli/src/tts/synthesize.cache.test.ts
index f31f4e77d8b..0707498689e 100644
--- a/packages/cli/src/tts/synthesize.cache.test.ts
+++ b/packages/cli/src/tts/synthesize.cache.test.ts
@@ -53,6 +53,14 @@ describe("synthesis script cache", () => {
     fs.rmSync(paths.home, { recursive: true, force: true });
   });
 
+  it("turns off onnxruntime telemetry for the synthesis process", async () => {
+    const { synthesize } = await import("./synthesize.js");
+    await synthesize("Hello", outputPath);
+
+    const options = vi.mocked(execFileSync).mock.calls.at(-1)?.[2];
+    expect(options?.env?.ORT_DISABLE_TELEMETRY).toBe("1");
+  });
+
   it("creates the script, removes only old script versions, and reuses the current cache", async () => {
     fs.writeFileSync(join(cacheDir, "synth-v2.py"), "old script");
     fs.writeFileSync(join(cacheDir, "notes.txt"), "keep");
diff --git a/packages/cli/src/tts/synthesize.ts b/packages/cli/src/tts/synthesize.ts
index a32f299ebd3..764084cc625 100644
--- a/packages/cli/src/tts/synthesize.ts
+++ b/packages/cli/src/tts/synthesize.ts
@@ -202,6 +202,7 @@ export async function synthesize(
         encoding: "utf-8",
         timeout: 300_000,
         stdio: ["pipe", "pipe", "pipe"],
+        env: { ...process.env, ORT_DISABLE_TELEMETRY: "1" },
       },
     );