Heat olive oil in a large pot or Dutch oven over medium heat.
Add chopped onion and sauté for 3-4 minutes until soft.
Add minced garlic and stir for another minute until fragrant.
Incorporate the ground beef and Italian sausage, cooking until browned (about 5-7 minutes). Drain excess fat if necessary.
Lower the heat and add the diced tomatoes (with juice), kidney beans, pinto beans, black beans, barbecue sauce, chili powder, cumin, smoked paprika, salt, and pepper. Stir well to combine.
Bring the mixture to a gentle simmer, then cover and reduce the heat to low. Cook for about 30-40 minutes, stirring occasionally to prevent sticking.
Once the beans are heated through and flavors have melded, taste and adjust seasoning if necessary.
Serve hot with a serving spoon.