In a large skillet over medium-high heat, brown the ground beef with diced onion and bell pepper, breaking up the meat as it cooks, about 7-8 minutes. Drain excess fat.
Add garlic to the skillet and cook for 1 minute until fragrant. Transfer everything to your slow cooker.
Add kidney beans, black beans, crushed tomatoes, tomato paste, and beef broth to the slow cooker.
Stir in chili powder, cumin, paprika, salt, and pepper. Mix everything together until well combined.
Cover and cook on LOW for 6-8 hours or HIGH for 3-4 hours, stirring occasionally if possible.
Taste and adjust seasonings as needed. Serve hot with your favorite toppings like shredded cheese, sour cream, diced onions, or crackers.