Chop the onion and spread it evenly across the bottom of the slow cooker.
Place the chicken breasts on top of the onion and sprinkle with the taco seasoning.
Add the beans, Rotel, corn, and tomato paste.
Pour the chicken broth over the ingredients and stir gently to combine.
Cover and cook on HIGH for 3-4 hours or LOW for 5-6 hours, or until the chicken is cooked through and tender.
Remove the chicken breasts from the slow cooker and shred using two forks or tongs.
Return the shredded chicken to the soup and stir until evenly incorporated.
Serve hot with your favorite toppings.