diff --git a/cli/compilers/compiler_worker.rs b/cli/compilers/compiler_worker.rs
index a1d2dc71c0..aa84c8695e 100644
--- a/cli/compilers/compiler_worker.rs
+++ b/cli/compilers/compiler_worker.rs
@@ -30,7 +30,7 @@ pub struct CompilerWorker(WebWorker);
 impl CompilerWorker {
   pub fn new(name: String, startup_data: StartupData, state: State) -> Self {
     let state_ = state.clone();
-    let mut worker = WebWorker::new(name, startup_data, state_);
+    let mut worker = WebWorker::new(name, startup_data, state_, false);
     {
       let isolate = &mut worker.isolate;
       ops::compiler::init(isolate, &state);
diff --git a/cli/js/compiler.ts b/cli/js/compiler.ts
index b3cd3a481e..91653a8e4e 100644
--- a/cli/js/compiler.ts
+++ b/cli/js/compiler.ts
@@ -391,12 +391,12 @@ async function wasmCompilerOnMessage({
 }
 
 function bootstrapTsCompilerRuntime(): void {
-  bootstrapWorkerRuntime("TS");
+  bootstrapWorkerRuntime("TS", false);
   globalThis.onmessage = tsCompilerOnMessage;
 }
 
 function bootstrapWasmCompilerRuntime(): void {
-  bootstrapWorkerRuntime("WASM");
+  bootstrapWorkerRuntime("WASM", false);
   globalThis.onmessage = wasmCompilerOnMessage;
 }
 
diff --git a/cli/js/lib.deno.shared_globals.d.ts b/cli/js/lib.deno.shared_globals.d.ts
index fd9f3691d6..ef450c2016 100644
--- a/cli/js/lib.deno.shared_globals.d.ts
+++ b/cli/js/lib.deno.shared_globals.d.ts
@@ -1080,6 +1080,46 @@ declare class Worker extends EventTarget {
     options?: {
       type?: "classic" | "module";
       name?: string;
+      /** UNSTABLE: New API. Expect many changes; most likely this
+       * field will be made into an object for more granular
+       * configuration of worker thread (permissions, import map, etc.).
+       *
+       * Set to `true` to make `Deno` namespace and all of its methods
+       * available to worker thread.
+       *
+       * Currently worker inherits permissions from main thread (permissions
+       * given using `--allow-*` flags).
+       * Configurable permissions are on the roadmap to be implemented.
+       *
+       * Example:
+       *    // mod.ts
+       *    const worker = new Worker("./deno_worker.ts", { type: "module", deno: true });
+       *    worker.postMessage({ cmd: "readFile", fileName: "./log.txt" });
+       *
+       *    // deno_worker.ts
+       *
+       *
+       *    self.onmessage = async function (e) {
+       *        const { cmd, fileName } = e.data;
+       *        if (cmd !== "readFile") {
+       *            throw new Error("Invalid command");
+       *        }
+       *        const buf = await Deno.readFile(fileName);
+       *        const fileContents = new TextDecoder().decode(buf);
+       *        console.log(fileContents);
+       *    }
+       *
+       *    // log.txt
+       *    hello world
+       *    hello world 2
+       *
+       *    // run program
+       *    $ deno run --allow-read mod.ts
+       *    hello world
+       *    hello world2
+       *
+       */
+      deno?: boolean;
     }
   );
   postMessage(message: any, transfer: ArrayBuffer[]): void;
diff --git a/cli/js/lib.deno.worker.d.ts b/cli/js/lib.deno.worker.d.ts
index a1e83af485..bba5f33219 100644
--- a/cli/js/lib.deno.worker.d.ts
+++ b/cli/js/lib.deno.worker.d.ts
@@ -3,6 +3,7 @@
 /* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any */
 
 /// <reference no-default-lib="true" />
+/// <reference lib="deno.ns" />
 /// <reference lib="deno.shared_globals" />
 /// <reference lib="esnext" />
 
@@ -15,6 +16,7 @@ declare interface DedicatedWorkerGlobalScope {
   name: typeof __workerMain.name;
   close: typeof __workerMain.close;
   postMessage: typeof __workerMain.postMessage;
+  Deno: typeof Deno;
 }
 
 declare const self: DedicatedWorkerGlobalScope & typeof globalThis;
diff --git a/cli/js/ops/worker_host.ts b/cli/js/ops/worker_host.ts
index d483a5313a..11e268152b 100644
--- a/cli/js/ops/worker_host.ts
+++ b/cli/js/ops/worker_host.ts
@@ -6,6 +6,7 @@ export function createWorker(
   specifier: string,
   hasSourceCode: boolean,
   sourceCode: string,
+  useDenoNamespace: boolean,
   name?: string
 ): { id: number } {
   return sendSync("op_create_worker", {
@@ -13,6 +14,7 @@ export function createWorker(
     hasSourceCode,
     sourceCode,
     name,
+    useDenoNamespace,
   });
 }
 
diff --git a/cli/js/runtime_worker.ts b/cli/js/runtime_worker.ts
index 1e7a9a67da..60c845a184 100644
--- a/cli/js/runtime_worker.ts
+++ b/cli/js/runtime_worker.ts
@@ -17,12 +17,23 @@ import {
   eventTargetProperties,
   setEventTargetData,
 } from "./globals.ts";
+import * as Deno from "./deno.ts";
 import * as webWorkerOps from "./ops/web_worker.ts";
 import { LocationImpl } from "./web/location.ts";
 import { log, assert, immutableDefine } from "./util.ts";
 import { MessageEvent, ErrorEvent } from "./web/workers.ts";
 import { TextEncoder } from "./web/text_encoding.ts";
 import * as runtime from "./runtime.ts";
+import { internalObject } from "./internals.ts";
+import { symbols } from "./symbols.ts";
+import { setSignals } from "./signals.ts";
+
+// FIXME(bartlomieju): duplicated in `runtime_main.ts`
+// TODO: factor out `Deno` global assignment to separate function
+// Add internal object to Deno object.
+// This is not exposed as part of the Deno types.
+// @ts-ignore
+Deno[symbols.internal] = internalObject;
 
 const encoder = new TextEncoder();
 
@@ -109,6 +120,7 @@ export const workerRuntimeGlobalProperties = {
 
 export function bootstrapWorkerRuntime(
   name: string,
+  useDenoNamespace: boolean,
   internalName?: string
 ): void {
   if (hasBootstrapped) {
@@ -128,7 +140,21 @@ export function bootstrapWorkerRuntime(
   immutableDefine(globalThis, "location", location);
   Object.freeze(globalThis.location);
 
-  // globalThis.Deno is not available in worker scope
-  delete globalThis.Deno;
-  assert(globalThis.Deno === undefined);
+  if (useDenoNamespace) {
+    Object.defineProperties(Deno, {
+      pid: readOnly(s.pid),
+      noColor: readOnly(s.noColor),
+      args: readOnly(Object.freeze(s.args)),
+    });
+    // Setup `Deno` global - we're actually overriding already
+    // existing global `Deno` with `Deno` namespace from "./deno.ts".
+    immutableDefine(globalThis, "Deno", Deno);
+    Object.freeze(globalThis.Deno);
+    Object.freeze(globalThis.Deno.core);
+    Object.freeze(globalThis.Deno.core.sharedQueue);
+    setSignals();
+  } else {
+    delete globalThis.Deno;
+    assert(globalThis.Deno === undefined);
+  }
 }
diff --git a/cli/js/web/workers.ts b/cli/js/web/workers.ts
index 0b7d4f4b6a..6fcab3fe3b 100644
--- a/cli/js/web/workers.ts
+++ b/cli/js/web/workers.ts
@@ -105,6 +105,7 @@ export interface Worker {
 export interface WorkerOptions {
   type?: "classic" | "module";
   name?: string;
+  deno?: boolean;
 }
 
 export class WorkerImpl extends EventTarget implements Worker {
@@ -146,10 +147,13 @@ export class WorkerImpl extends EventTarget implements Worker {
     }
     */
 
+    const useDenoNamespace = options ? !!options.deno : false;
+
     const { id } = createWorker(
       specifier,
       hasSourceCode,
       sourceCode,
+      useDenoNamespace,
       options?.name
     );
     this.#id = id;
diff --git a/cli/ops/worker_host.rs b/cli/ops/worker_host.rs
index dafd969b2e..a4db5e27fb 100644
--- a/cli/ops/worker_host.rs
+++ b/cli/ops/worker_host.rs
@@ -3,6 +3,7 @@ use super::dispatch_json::{Deserialize, JsonOp, Value};
 use crate::fmt_errors::JSError;
 use crate::global_state::GlobalState;
 use crate::op_error::OpError;
+use crate::ops::io::get_stdio;
 use crate::permissions::DenoPermissions;
 use crate::startup_data;
 use crate::state::State;
@@ -37,17 +38,31 @@ fn create_web_worker(
   global_state: GlobalState,
   permissions: DenoPermissions,
   specifier: ModuleSpecifier,
+  has_deno_namespace: bool,
 ) -> Result<WebWorker, ErrBox> {
   let state =
     State::new_for_worker(global_state, Some(permissions), specifier)?;
 
-  let mut worker =
-    WebWorker::new(name.to_string(), startup_data::deno_isolate_init(), state);
+  if has_deno_namespace {
+    let mut s = state.borrow_mut();
+    let (stdin, stdout, stderr) = get_stdio();
+    s.resource_table.add("stdin", Box::new(stdin));
+    s.resource_table.add("stdout", Box::new(stdout));
+    s.resource_table.add("stderr", Box::new(stderr));
+  }
+
+  let mut worker = WebWorker::new(
+    name.clone(),
+    startup_data::deno_isolate_init(),
+    state,
+    has_deno_namespace,
+  );
+
   // Instead of using name for log we use `worker-${id}` because
   // WebWorkers can have empty string as name.
   let script = format!(
-    "bootstrapWorkerRuntime(\"{}\", \"worker-{}\")",
-    name, worker_id
+    "bootstrapWorkerRuntime(\"{}\", {}, \"worker-{}\")",
+    name, worker.has_deno_namespace, worker_id
   );
   worker.execute(&script)?;
 
@@ -61,8 +76,8 @@ fn run_worker_thread(
   global_state: GlobalState,
   permissions: DenoPermissions,
   specifier: ModuleSpecifier,
-  has_source_code: bool,
-  source_code: String,
+  has_deno_namespace: bool,
+  maybe_source_code: Option<String>,
 ) -> Result<(JoinHandle<()>, WebWorkerHandle), ErrBox> {
   let (handle_sender, handle_receiver) =
     std::sync::mpsc::sync_channel::<Result<WebWorkerHandle, ErrBox>>(1);
@@ -80,6 +95,7 @@ fn run_worker_thread(
       global_state,
       permissions,
       specifier.clone(),
+      has_deno_namespace,
     );
 
     if let Err(err) = result {
@@ -108,7 +124,7 @@ fn run_worker_thread(
     // TODO: run with using select with terminate
 
     // Execute provided source code immediately
-    let result = if has_source_code {
+    let result = if let Some(source_code) = maybe_source_code {
       worker.execute(&source_code)
     } else {
       // TODO(bartlomieju): add "type": "classic", ie. ability to load
@@ -146,6 +162,7 @@ struct CreateWorkerArgs {
   specifier: String,
   has_source_code: bool,
   source_code: String,
+  use_deno_namespace: bool,
 }
 
 /// Create worker as the host
@@ -157,9 +174,13 @@ fn op_create_worker(
   let args: CreateWorkerArgs = serde_json::from_value(args)?;
 
   let specifier = args.specifier.clone();
-  let has_source_code = args.has_source_code;
-  let source_code = args.source_code.clone();
+  let maybe_source_code = if args.has_source_code {
+    Some(args.source_code.clone())
+  } else {
+    None
+  };
   let args_name = args.name;
+  let use_deno_namespace = args.use_deno_namespace;
   let parent_state = state.clone();
   let mut state = state.borrow_mut();
   let global_state = state.global_state.clone();
@@ -179,8 +200,8 @@ fn op_create_worker(
     global_state,
     permissions,
     module_specifier,
-    has_source_code,
-    source_code,
+    use_deno_namespace,
+    maybe_source_code,
   )
   .map_err(|e| OpError::other(e.to_string()))?;
   // At this point all interactions with worker happen using thread
diff --git a/cli/tests/subdir/deno_worker.ts b/cli/tests/subdir/deno_worker.ts
new file mode 100644
index 0000000000..6a57c47f0f
--- /dev/null
+++ b/cli/tests/subdir/deno_worker.ts
@@ -0,0 +1,7 @@
+onmessage = function (e): void {
+  if (typeof self.Deno === "undefined") {
+    throw new Error("Deno namespace not available in worker");
+  }
+
+  postMessage(e.data);
+};
diff --git a/cli/tests/subdir/non_deno_worker.js b/cli/tests/subdir/non_deno_worker.js
new file mode 100644
index 0000000000..773721560d
--- /dev/null
+++ b/cli/tests/subdir/non_deno_worker.js
@@ -0,0 +1,7 @@
+onmessage = function (e) {
+  if (typeof self.Deno !== "undefined") {
+    throw new Error("Deno namespace unexpectedly available in worker");
+  }
+
+  postMessage(e.data);
+};
diff --git a/cli/tests/workers_test.out b/cli/tests/workers_test.out
index d3c25d3ddc..9032262834 100644
--- a/cli/tests/workers_test.out
+++ b/cli/tests/workers_test.out
@@ -1,4 +1,4 @@
-running 8 tests
+running 9 tests
 test worker terminate ... ok [WILDCARD]
 test worker nested ... ok [WILDCARD]
 test worker throws when executing ... ok [WILDCARD]
@@ -7,5 +7,6 @@ test worker terminate busy loop ... ok [WILDCARD]
 test worker race condition ... ok [WILDCARD]
 test worker is event listener ... ok [WILDCARD]
 test worker scope is event listener ... ok [WILDCARD]
+test worker with Deno namespace ... ok [WILDCARD]
 
-test result: ok. 8 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out [WILDCARD]
+test result: ok. 9 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out [WILDCARD]
diff --git a/cli/tests/workers_test.ts b/cli/tests/workers_test.ts
index c51adcf757..c4b93db3c5 100644
--- a/cli/tests/workers_test.ts
+++ b/cli/tests/workers_test.ts
@@ -257,3 +257,36 @@ Deno.test({
     worker.terminate();
   },
 });
+
+Deno.test({
+  name: "worker with Deno namespace",
+  fn: async function (): Promise<void> {
+    const promise = createResolvable();
+    const promise2 = createResolvable();
+
+    const regularWorker = new Worker("../tests/subdir/non_deno_worker.js", {
+      type: "module",
+    });
+    const denoWorker = new Worker("../tests/subdir/deno_worker.ts", {
+      type: "module",
+      deno: true,
+    });
+
+    regularWorker.onmessage = (e): void => {
+      assertEquals(e.data, "Hello World");
+      regularWorker.terminate();
+      promise.resolve();
+    };
+
+    denoWorker.onmessage = (e): void => {
+      assertEquals(e.data, "Hello World");
+      denoWorker.terminate();
+      promise2.resolve();
+    };
+
+    regularWorker.postMessage("Hello World");
+    await promise;
+    denoWorker.postMessage("Hello World");
+    await promise2;
+  },
+});
diff --git a/cli/web_worker.rs b/cli/web_worker.rs
index 795409175d..24318fc59e 100644
--- a/cli/web_worker.rs
+++ b/cli/web_worker.rs
@@ -77,10 +77,16 @@ pub struct WebWorker {
   event_loop_idle: bool,
   terminate_rx: mpsc::Receiver<()>,
   handle: WebWorkerHandle,
+  pub has_deno_namespace: bool,
 }
 
 impl WebWorker {
-  pub fn new(name: String, startup_data: StartupData, state: State) -> Self {
+  pub fn new(
+    name: String,
+    startup_data: StartupData,
+    state: State,
+    has_deno_namespace: bool,
+  ) -> Self {
     let state_ = state.clone();
     let mut worker = Worker::new(name, startup_data, state_);
 
@@ -105,6 +111,7 @@ impl WebWorker {
       event_loop_idle: false,
       terminate_rx,
       handle,
+      has_deno_namespace,
     };
 
     let handle = web_worker.thread_safe_handle();
@@ -124,6 +131,22 @@ impl WebWorker {
       ops::errors::init(isolate, &state);
       ops::timers::init(isolate, &state);
       ops::fetch::init(isolate, &state);
+
+      if has_deno_namespace {
+        let op_registry = isolate.op_registry.clone();
+        ops::runtime_compiler::init(isolate, &state);
+        ops::fs::init(isolate, &state);
+        ops::fs_events::init(isolate, &state);
+        ops::plugins::init(isolate, &state, op_registry);
+        ops::net::init(isolate, &state);
+        ops::tls::init(isolate, &state);
+        ops::os::init(isolate, &state);
+        ops::permissions::init(isolate, &state);
+        ops::process::init(isolate, &state);
+        ops::random::init(isolate, &state);
+        ops::signal::init(isolate, &state);
+        ops::tty::init(isolate, &state);
+      }
     }
 
     web_worker
@@ -238,8 +261,11 @@ mod tests {
       "TEST".to_string(),
       startup_data::deno_isolate_init(),
       state,
+      false,
     );
-    worker.execute("bootstrapWorkerRuntime(\"TEST\")").unwrap();
+    worker
+      .execute("bootstrapWorkerRuntime(\"TEST\", false)")
+      .unwrap();
     worker
   }
   #[test]