In a large slow cooker, combine chicken, onion, corn, bell pepper, tomatoes, beans, and garlic.
In a large bowl, whisk together chicken stock, barbecue sauce, salt, and pepper.
Pour chicken stock mixture into slow cooker and stir to combine.
Cover and cook on LOW heat for 5 hours.
Remove chicken from slow cooker and shred using two forks. Return to slow cooker.
Serve soup topped with shredded cheese.