diff --git a/Lib/ensurepip/__init__.py b/Lib/ensurepip/__init__.py
index 3fbe8b2a5b1367..a4c46ec65fe8db 100644
--- a/Lib/ensurepip/__init__.py
+++ b/Lib/ensurepip/__init__.py
@@ -90,8 +90,16 @@ def _run_pip(args, additional_paths=None):
 sys.argv[1:] = {args}
 runpy.run_module("pip", run_name="__main__", alter_sys=True)
 """
-    return subprocess.run([sys.executable, '-W', 'ignore::DeprecationWarning',
-                           "-c", code], check=True).returncode
+
+    cmd = [
+      sys.executable,
+      # run code in isolated mode if currently running isolated
+      *([ '-I'] if sys.flags.isolated else []),
+      '-W', 'ignore::DeprecationWarning',
+      '-c',
+      code ]
+
+    return subprocess.run( cmd, check = True ).returncode
 
 
 def version():
diff --git a/Misc/NEWS.d/next/Library/2022-01-03-15-07-06.bpo-46197.Z0djv6.rst b/Misc/NEWS.d/next/Library/2022-01-03-15-07-06.bpo-46197.Z0djv6.rst
new file mode 100644
index 00000000000000..3a4f5e0edf7bf6
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-01-03-15-07-06.bpo-46197.Z0djv6.rst
@@ -0,0 +1 @@
+Fix :mod:`ensurepip` environment isolation for sub-process.
\ No newline at end of file