Preheat the oven to 400 degrees F (200 degrees C).

Mix barbecue sauce, honey, ketchup, and onion together in a medium bowl until well combined.

Place chicken in a 9x13-inch baking dish. Pour sauce over chicken, then cover the dish with foil.

Bake in the preheated oven until no longer pink in the center and the juices run clear, 45 minutes to 1 hour. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).