diff --git a/src/lib/onboard.ts b/src/lib/onboard.ts
index f4584f1266a..78b2b3feb85 100644
--- a/src/lib/onboard.ts
+++ b/src/lib/onboard.ts
@@ -364,6 +364,7 @@ import type {
   OpenShellInstallResult,
 } from "./onboard/openshell-install";
 import { decidePolicyCarryForward } from "./onboard/policy-carryforward";
+import { resolveSandboxGpuMode, type SandboxGpuFlag, type SandboxGpuMode } from "./onboard/sandbox-gpu-mode";
 import type { SelectionDrift } from "./onboard/selection-drift";
 import type {
   ModelCatalogFetchResult,
@@ -1240,9 +1241,6 @@ function shouldAllowOpenshellAboveBlueprintMax(
   return shouldUseOpenshellDevChannel(platform, env) && isOpenshellDevVersion(versionOutput);
 }
 
-type SandboxGpuMode = "auto" | "1" | "0";
-type SandboxGpuFlag = "enable" | "disable" | null;
-
 type SandboxGpuConfig = {
   mode: SandboxGpuMode;
   hostGpuDetected: boolean;
@@ -1287,9 +1285,7 @@ function resolveSandboxGpuConfig(
     errors.push("NEMOCLAW_SANDBOX_GPU must be one of: auto, 1, 0.");
   }
 
-  let mode: SandboxGpuMode = envMode ?? "auto";
-  if (options.flag === "enable") mode = "1";
-  if (options.flag === "disable") mode = "0";
+  let mode = resolveSandboxGpuMode({ envMode, gpu, flag: options.flag });
 
   const device = (options.device ?? env.NEMOCLAW_SANDBOX_GPU_DEVICE ?? "").trim() || null;
   if (device && mode === "0") {
@@ -10035,6 +10031,8 @@ async function onboard(opts: OnboardOptions = {}): Promise<void> {
             ? "  GPU passthrough requested; passing --gpu to OpenShell gateway and sandbox creation."
             : "  NVIDIA GPU detected; enabling OpenShell GPU passthrough. Use --no-gpu to opt out.",
       );
+    } else if (gpu?.platform === "jetson") {
+      note("  GPU sandbox passthrough disabled by default on Jetson.");
     } else if (process.platform === "linux") {
       // Hint when hardware is present but drivers are missing.
       try {
diff --git a/src/lib/onboard/sandbox-gpu-mode.ts b/src/lib/onboard/sandbox-gpu-mode.ts
new file mode 100644
index 00000000000..158fcfee421
--- /dev/null
+++ b/src/lib/onboard/sandbox-gpu-mode.ts
@@ -0,0 +1,20 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+import type { GpuDetection } from "../inference/nim";
+
+export type SandboxGpuMode = "auto" | "1" | "0";
+export type SandboxGpuFlag = "enable" | "disable" | null;
+
+export function resolveSandboxGpuMode(args: {
+  envMode: SandboxGpuMode | null;
+  gpu: GpuDetection | null | undefined;
+  flag?: SandboxGpuFlag;
+}): SandboxGpuMode {
+  let mode: SandboxGpuMode = args.envMode ?? "auto";
+  // GPU sandbox passthrough does not currently work on Jetson; disable by default
+  if (args.gpu?.platform === "jetson" && args.envMode === null) mode = "0";
+  if (args.flag === "enable") mode = "1";
+  if (args.flag === "disable") mode = "0";
+  return mode;
+}
diff --git a/test/onboard.test.ts b/test/onboard.test.ts
index f8ce6b019a0..4f6eda15fac 100644
--- a/test/onboard.test.ts
+++ b/test/onboard.test.ts
@@ -386,6 +386,17 @@ describe("onboard helpers", () => {
     expect(forced.errors.join("\n")).toContain("no NVIDIA GPU");
   });
 
+  it("defaults to CPU sandbox on Jetson when NEMOCLAW_SANDBOX_GPU is unset", () => {
+    const jetson = { type: "nvidia", platform: "jetson" as const };
+    expect(resolveSandboxGpuConfig(jetson, { env: {} }).sandboxGpuEnabled).toBe(false);
+    // Explicit env opt-in still wins over the platform default.
+    expect(
+      resolveSandboxGpuConfig(jetson, { env: { NEMOCLAW_SANDBOX_GPU: "1" } }).sandboxGpuEnabled,
+    ).toBe(true);
+    // --gpu also overrides the platform default.
+    expect(resolveSandboxGpuConfig(jetson, { flag: "enable", env: {} }).mode).toBe("1");
+  });
+
   it("resumes sandbox GPU auto mode without turning CPU fallback into explicit opt-out", () => {
     const resumedAuto = getResumeSandboxGpuOverrides(
       { sandboxGpuMode: "auto", sandboxGpuDevice: null },