Pat the beef roast dry with paper towels. Season all sides evenly with salt and black pepper.
Heat olive oil in a large skillet over medium-high heat. Sear the beef roast on all sides until browned, about 3-4 minutes per side.
Place the sliced onion, carrots, and celery in the bottom of the slow cooker.
Add the minced garlic on top of the vegetables.
Place the seared beef roast on top of the vegetables in the slow cooker.
Pour the beef broth and Worcestershire sauce over the roast.
Add the rosemary and thyme sprigs on top of the roast.
Cover the slow cooker with the lid and cook on low for 8 hours, or until the beef is tender and easily shredded with a fork.
Remove the beef roast from the slow cooker and let it rest for 10 minutes before slicing.
Serve the sliced roast beef with the cooked vegetables and spoon some of the cooking juices over the top.