Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Drain the bacon slices on paper towels.
Combine pork and beans, onion, brown sugar, Worcestershire sauce, and mustard in a 2-quart casserole dish. Chop drained bacon and stir into pork and beans mixture. Cover dish with aluminum foil.
