diff --git a/.changeset/fix-c3-pnpm-11-auto-update-loop.md b/.changeset/fix-c3-pnpm-11-auto-update-loop.md
new file mode 100644
index 0000000000..8f6ba9e083
--- /dev/null
+++ b/.changeset/fix-c3-pnpm-11-auto-update-loop.md
@@ -0,0 +1,9 @@
+---
+"create-cloudflare": patch
+---
+
+Fix infinite loop when running C3 with pnpm 11
+
+When invoked via `pnpm create cloudflare@latest`, C3 checks npm for a newer version and re-launches itself with the latest version if one is available. pnpm 11 enables the `minimumReleaseAge` supply-chain protection by default, so `pnpm create cloudflare@latest` will not resolve a version published in the last 24 hours. When the npm `latest` tag points at a version newer than what pnpm is willing to install, the update check stayed true and C3 re-launched itself forever.
+
+The relaunched process is now marked so it never re-runs the auto-update check, ensuring C3 starts up after at most one relaunch regardless of the package manager's version resolution.
diff --git a/packages/create-cloudflare/src/cli.ts b/packages/create-cloudflare/src/cli.ts
index 56cdf1d682..9a1fc24ada 100644
--- a/packages/create-cloudflare/src/cli.ts
+++ b/packages/create-cloudflare/src/cli.ts
@@ -10,12 +10,11 @@ import {
 	logRaw,
 	startSection,
 } from "@cloudflare/cli-shared-helpers";
-import { runCommand } from "@cloudflare/cli-shared-helpers/command";
 import { CancelError } from "@cloudflare/cli-shared-helpers/error";
 import { maybeAppendWranglerToGitIgnore } from "@cloudflare/cli-shared-helpers/gitignore";
 import { isInteractive } from "@cloudflare/cli-shared-helpers/interactive";
 import { cliDefinition, parseArgs, processArgument } from "helpers/args";
-import { C3_DEFAULTS, isUpdateAvailable } from "helpers/cli";
+import { C3_DEFAULTS, isUpdateAvailable, runLatest } from "helpers/cli";
 import { runWranglerCommand } from "helpers/command";
 import {
 	detectPackageManager,
@@ -46,8 +45,6 @@ import { addTypes } from "./workers";
 import { updateWranglerConfig } from "./wrangler/config";
 import type { C3Args, C3Context } from "types";
 
-const { npm } = detectPackageManager();
-
 export const main = async (argv: string[]) => {
 	const result = await parseArgs(argv);
 
@@ -79,6 +76,12 @@ export const main = async (argv: string[]) => {
 
 	if (
 		args.autoUpdate &&
+		// If this process was already spawned by `runLatest`, don't try to update
+		// again. Otherwise, package managers that resolve `cloudflare@latest` to a
+		// version older than the npm `latest` tag (e.g. pnpm 11's `minimumReleaseAge`
+		// supply-chain protection) would cause `isUpdateAvailable()` to stay true and
+		// re-spawn C3 forever.
+		!process.env.CREATE_CLOUDFLARE_RELAUNCHED &&
 		!process.env.VITEST &&
 		!process.env.CI &&
 		isInteractive() &&
@@ -96,19 +99,6 @@ export const main = async (argv: string[]) => {
 	}
 };
 
-// Spawn a separate process running the most recent version of c3
-export const runLatest = async () => {
-	const args = process.argv.slice(2);
-
-	// the parsing logic of `npm create` requires `--` to be supplied
-	// before any flags intended for the target command.
-	if (npm === "npm") {
-		args.unshift("--");
-	}
-
-	await runCommand([npm, "create", "cloudflare@latest", ...args]);
-};
-
 // Entrypoint to c3
 export const runCli = async (args: Partial<C3Args>) => {
 	printBanner(args);
diff --git a/packages/create-cloudflare/src/helpers/__tests__/cli.test.ts b/packages/create-cloudflare/src/helpers/__tests__/cli.test.ts
index f77e9fb0b7..3136675cc4 100644
--- a/packages/create-cloudflare/src/helpers/__tests__/cli.test.ts
+++ b/packages/create-cloudflare/src/helpers/__tests__/cli.test.ts
@@ -1,12 +1,15 @@
+import { runCommand } from "@cloudflare/cli-shared-helpers/command";
 import { SemVer } from "semver";
 import { getGlobalDispatcher, MockAgent, setGlobalDispatcher } from "undici";
 import { afterEach, beforeEach, describe, test, vi } from "vitest";
 import { version as currentVersion } from "../../../package.json";
-import { isUpdateAvailable } from "../cli";
-import { mockSpinner } from "./mocks";
+import { isUpdateAvailable, runLatest } from "../cli";
+import { mockPackageManager, mockSpinner } from "./mocks";
 
 vi.mock("process");
+vi.mock("@cloudflare/cli-shared-helpers/command");
 vi.mock("@cloudflare/cli-shared-helpers/interactive");
+vi.mock("which-pm-runs");
 
 beforeEach(() => {
 	mockSpinner();
@@ -78,3 +81,20 @@ describe("isUpdateAvailable", () => {
 			);
 	}
 });
+
+describe("runLatest", () => {
+	beforeEach(() => {
+		mockPackageManager("pnpm", "11.0.0");
+		vi.mocked(runCommand).mockResolvedValue("");
+	});
+
+	test("marks the relaunched process so it does not update again", async ({
+		expect,
+	}) => {
+		await runLatest();
+
+		expect(runCommand).toHaveBeenCalledTimes(1);
+		const [, opts] = vi.mocked(runCommand).mock.calls[0];
+		expect(opts?.env).toEqual({ CREATE_CLOUDFLARE_RELAUNCHED: "true" });
+	});
+});
diff --git a/packages/create-cloudflare/src/helpers/cli.ts b/packages/create-cloudflare/src/helpers/cli.ts
index 2c2967b410..be09b9d22a 100644
--- a/packages/create-cloudflare/src/helpers/cli.ts
+++ b/packages/create-cloudflare/src/helpers/cli.ts
@@ -1,10 +1,12 @@
 import { updateStatus, warn } from "@cloudflare/cli-shared-helpers";
 import { blue } from "@cloudflare/cli-shared-helpers/colors";
+import { runCommand } from "@cloudflare/cli-shared-helpers/command";
 import {
 	spinner,
 	spinnerFrames,
 } from "@cloudflare/cli-shared-helpers/interactive";
 import Haikunator from "haikunator";
+import { detectPackageManager } from "helpers/packageManagers";
 import { getLatestPackageVersion } from "helpers/packages";
 import open from "open";
 import semver from "semver";
@@ -48,6 +50,25 @@ export const isUpdateAvailable = async () => {
 	}
 };
 
+// Spawn a separate process running the most recent version of c3
+export const runLatest = async () => {
+	const { npm } = detectPackageManager();
+	const args = process.argv.slice(2);
+
+	// the parsing logic of `npm create` requires `--` to be supplied
+	// before any flags intended for the target command.
+	if (npm === "npm") {
+		args.unshift("--");
+	}
+
+	await runCommand([npm, "create", "cloudflare@latest", ...args], {
+		// Mark the spawned process so it doesn't attempt to update and re-spawn
+		// again, which would loop indefinitely when the package manager keeps
+		// resolving the same version of `cloudflare@latest`.
+		env: { CREATE_CLOUDFLARE_RELAUNCHED: "true" },
+	});
+};
+
 export const C3_DEFAULTS: C3Args = {
 	projectName: new Haikunator().haikunate({ tokenHex: true }),
 	category: "hello-world",
diff --git a/packages/create-cloudflare/turbo.json b/packages/create-cloudflare/turbo.json
index 04e2b5ebf5..918fd28c77 100644
--- a/packages/create-cloudflare/turbo.json
+++ b/packages/create-cloudflare/turbo.json
@@ -5,6 +5,7 @@
 		"build": {
 			"env": [
 				"npm_config_user_agent",
+				"CREATE_CLOUDFLARE_RELAUNCHED",
 				"CREATE_CLOUDFLARE_TELEMETRY_DISABLED",
 				"CREATE_CLOUDFLARE_TELEMETRY_DEBUG",
 				"SPARROW_SOURCE_KEY"