Heat a large skillet over medium-high heat. Cook and crumble the beef until no longer pink. Drain excess grease. Add the onions and garlic. Cook, stirring occasionally, until onions soften.
Add the taco seasoning and stir to combine. Transfer into the Crockpot.
Add the black beans, red enchilada sauce, diced tomatoes and green chiles, frozen corn, beef broth, uncooked rice, and bell peppers. Stir together to evenly distribute and so it cooks evenly.
Cover and cook on low for 4-5 hours or high for 2 ½-3 hours, until rice is tender.
Sprinkle the cheese on top. Cover with lid for about 5 minutes to allow the cheese to melt.