Place the beef stew meat, sweet potatoes, carrots, celery, onion, and garlic into the slow cooker.
Add the thyme, Worcestershire sauce, salt, and black pepper.
Pour the beef broth over the top and stir gently to combine everything.
Cover and cook on low for 8 hours until the beef is tender and the vegetables are soft.
Stir in the frozen peas during the last 30 minutes of cooking so they warm through but keep their color.