In a skillet over medium heat, heat the olive oil. Add the chopped onion and sauté for 2-3 minutes until translucent.
Add the minced garlic and cook for another minute.
Add the ground beef and cook until browned, about 5-7 minutes. Drain excess fat if necessary.
Transfer the cooked meat mixture to the crockpot.
Add the black beans, kidney beans, diced tomatoes, tomato paste, and beef broth to the crockpot.
Stir in the chili powder, cumin, paprika, cayenne pepper, and season with salt and pepper.
Add the chopped bell pepper and stir well to combine.
Cover the crockpot and set it on low for 6 hours or high for 3 hours.
Once done, taste and adjust seasoning if necessary.