Heat olive oil in a large skillet over medium-high heat. Season the beef roast with salt, pepper, garlic powder, onion powder, thyme, and rosemary. Sear the roast in the skillet for about 4-5 minutes on each side until browned.
Place the chopped onion, carrots, and potatoes in the bottom of the slow cooker.
Transfer the seared roast on top of the vegetables in the slow cooker.
In a bowl, mix together the beef broth and Worcestershire sauce. Pour this mixture over the roast and vegetables.
Cover and cook on low for 8-10 hours or on high for 4-6 hours, until the meat is tender and easily shreds with a fork.
If you prefer a thicker gravy, mix cornstarch and water in a small bowl until smooth. Stir this mixture into the slow cooker during the last 30 minutes of cooking.
Once done, remove the roast and vegetables from the slow cooker. Let the roast rest for a few minutes before slicing. Serve with the gravy spooned over the top.