Place the chicken breasts in the bottom of the slow cooker. Add the diced onion, red bell pepper, and minced garlic on top.
Pour in the drained black beans, diced tomatoes with their juice, and chicken broth. Sprinkle the chili powder, cumin, oregano, salt, and black pepper over everything.
Cover and cook on low for 6 to 7 hours or on high for 3 to 4 hours, until the chicken is fully cooked and shreds easily.
Remove the chicken, shred it with two forks, and return it to the slow cooker. Stir in the frozen corn and let it heat through for 10 to 15 minutes.
Taste and adjust salt if needed. Serve hot with chopped cilantro and lime wedges.