Cut the rack of ribs into individual pieces, if necessary, to fit in the slow cooker.
In a mixing bowl, combine the barbecue sauce, brown sugar, apple cider vinegar, Worcestershire sauce, Dijon mustard, smoked paprika, garlic powder, onion powder, salt, and pepper. Stir until well combined.
Place the ribs in the slow cooker, and pour the barbecue sauce mixture over them, ensuring they are evenly coated.
Cover the slow cooker and cook on low for 6-8 hours or on high for 4-6 hours, until the meat is tender and easily pulls away from the bones.
Once the ribs are cooked, carefully transfer them to a baking sheet lined with foil.
Preheat the oven to broil. Brush the ribs with additional barbecue sauce from the slow cooker.
Broil the ribs for a few minutes until they become caramelized and slightly charred, keeping a close eye on them to prevent burning.
Remove the ribs from the oven and let them rest for a few minutes before serving.
Serve the Slow Cooker BBQ Pork Ribs hot, and optionally, brush them with more barbecue sauce before serving.
