diff --git a/packages/cli-workflow/src/__tests__/thread-start-cwd-cli.test.ts b/packages/cli-workflow/src/__tests__/thread-start-cwd-cli.test.ts
new file mode 100644
index 0000000..27a35c8
--- /dev/null
+++ b/packages/cli-workflow/src/__tests__/thread-start-cwd-cli.test.ts
@@ -0,0 +1,148 @@
+import { execFileSync } from "node:child_process";
+import { mkdir, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import type { CasRef, StartNodePayload, ThreadId } from "@uncaged/workflow-protocol";
+import { describe, expect, test } from "vitest";
+import { cmdThreadStart } from "../commands/thread.js";
+import { createUwfStore, loadThreadsIndex } from "../store.js";
+
+describe("thread start --cwd CLI option", () => {
+  let tmpDir: string;
+  let storageRoot: string;
+
+  async function setupTestEnv() {
+    tmpDir = join(tmpdir(), `uwf-test-cwd-cli-${Date.now()}`);
+    storageRoot = join(tmpDir, "storage");
+    await mkdir(storageRoot, { recursive: true });
+  }
+
+  async function teardown() {
+    if (tmpDir) {
+      await rm(tmpDir, { recursive: true, force: true });
+    }
+  }
+
+  async function createTestWorkflow(): Promise<string> {
+    const workflowYaml = `
+name: test-cwd-cli
+description: Test workflow for CLI cwd option
+roles:
+  planner:
+    description: Plans the work
+    goal: Plan implementation
+    capabilities: ["planning"]
+    procedure: Plan
+    output: |
+      $status: "ready"
+    frontmatter:
+      type: object
+      required: ["$status"]
+      properties:
+        $status: { type: string }
+graph:
+  $START:
+    _:
+      role: planner
+      prompt: "Plan the work"
+      location: null
+  planner:
+    _:
+      role: $END
+      prompt: "Done"
+      location: null
+`;
+
+    const workflowPath = join(tmpDir, "test-cwd-cli.yaml");
+    await writeFile(workflowPath, workflowYaml, "utf8");
+    return workflowPath;
+  }
+
+  async function getStartNodeCwd(threadId: string): Promise<string> {
+    const uwf = await createUwfStore(storageRoot);
+    const index = await loadThreadsIndex(storageRoot);
+    const headHash = index[threadId as ThreadId];
+    expect(headHash).toBeDefined();
+
+    const startNode = uwf.store.get(headHash as CasRef);
+    expect(startNode).not.toBe(null);
+    expect(startNode?.type).toBe(uwf.schemas.startNode);
+
+    const startPayload = startNode?.payload as StartNodePayload;
+    return startPayload.cwd;
+  }
+
+  test("thread start with custom cwd via cmdThreadStart", async () => {
+    await setupTestEnv();
+
+    const workflowPath = await createTestWorkflow();
+    const testCwd = "/test/custom/path";
+
+    const result = await cmdThreadStart(storageRoot, workflowPath, "test prompt", tmpDir, testCwd);
+
+    expect(result.thread).toBeDefined();
+    const actualCwd = await getStartNodeCwd(result.thread);
+    expect(actualCwd).toBe(testCwd);
+
+    await teardown();
+  });
+
+  test("thread start without cwd defaults to process.cwd()", async () => {
+    await setupTestEnv();
+
+    const workflowPath = await createTestWorkflow();
+
+    // Call without cwd parameter (it defaults to process.cwd())
+    const result = await cmdThreadStart(storageRoot, workflowPath, "test prompt", tmpDir);
+
+    expect(result.thread).toBeDefined();
+    const actualCwd = await getStartNodeCwd(result.thread);
+    expect(actualCwd).toBe(process.cwd());
+
+    await teardown();
+  });
+
+  test("thread start with relative path fails", async () => {
+    await setupTestEnv();
+
+    const workflowPath = await createTestWorkflow();
+
+    await expect(
+      cmdThreadStart(storageRoot, workflowPath, "test", tmpDir, "relative/path"),
+    ).rejects.toThrow();
+
+    await teardown();
+  });
+
+  test("CLI accepts --cwd option without error", async () => {
+    await setupTestEnv();
+
+    const workflowPath = await createTestWorkflow();
+    const testCwd = "/test/cli/path";
+    const uwfBin = join(process.cwd(), "dist", "cli.js");
+
+    // Register the workflow
+    execFileSync("node", [uwfBin, "workflow", "add", workflowPath], {
+      env: { ...process.env, UWF_STORAGE_ROOT: storageRoot },
+      encoding: "utf8",
+    });
+
+    // Verify CLI accepts --cwd option (no error thrown)
+    const output = execFileSync(
+      "node",
+      [uwfBin, "thread", "start", "test-cwd-cli", "-p", "test prompt", "--cwd", testCwd],
+      {
+        env: { ...process.env, UWF_STORAGE_ROOT: storageRoot },
+        encoding: "utf8",
+      },
+    );
+
+    const result = JSON.parse(output);
+    expect(result.thread).toBeDefined();
+    expect(result.workflow).toBeDefined();
+
+    // The fact that we got here without throwing means CLI accepted the --cwd option
+    // The actual cwd functionality is tested by the other tests using cmdThreadStart directly
+    await teardown();
+  });
+});
diff --git a/packages/cli-workflow/src/cli.ts b/packages/cli-workflow/src/cli.ts
index 1792f76..a351632 100755
--- a/packages/cli-workflow/src/cli.ts
+++ b/packages/cli-workflow/src/cli.ts
@@ -118,10 +118,17 @@ thread
   .description("Create a thread without executing")
   .argument("<workflow>", "Workflow name or hash")
   .requiredOption("-p, --prompt <text>", "User prompt")
-  .action((workflow: string, opts: { prompt: string }) => {
+  .option("--cwd <path>", "Working directory for thread execution (default: process.cwd())")
+  .action((workflow: string, opts: { prompt: string; cwd: string | undefined }) => {
     const storageRoot = resolveStorageRoot();
     runAction(async () => {
-      const result = await cmdThreadStart(storageRoot, workflow, opts.prompt, process.cwd());
+      const result = await cmdThreadStart(
+        storageRoot,
+        workflow,
+        opts.prompt,
+        process.cwd(),
+        opts.cwd ?? process.cwd(),
+      );
       writeOutput(result);
     });
   });