In a large skillet over medium-high heat, brown the ground beef with the diced onion and bell pepper until the meat is no longer pink, about 8-10 minutes. Drain excess fat.
Add the minced garlic to the skillet and cook for 1 minute until fragrant.
Transfer the beef mixture to your slow cooker. Add the kidney beans, black beans, crushed tomatoes, tomato paste, beef broth, chili powder, cumin, paprika, salt, and pepper.
Stir everything together until well combined. Cover and cook on LOW for 6-8 hours or on HIGH for 3-4 hours.
Taste and adjust seasonings as needed. Serve hot with your favorite toppings like shredded cheese, sour cream, and sliced green onions.