Mix beer, cream of mushroom soup, onion soup mix, onion, and garlic together in a slow cooker. Season beef chuck roast with salt and pepper, and place in the slow cooker. Arrange the carrots and potatoes around the meat.
Cook on Low for 6 hours, then add the celery. Continue cooking until the roast falls apart easily and the potatoes are softened, about 2 hours more. Serve the meat and vegetables with the remaining gravy on top.