Combine kidney beans, chili beans, diced tomatoes, onion, and tomato paste in a large stockpot; cook and stir over low heat until onion is tender, about 10 minutes.
Heat a large skillet over medium-high heat. Cook and stir beef and sausage in the hot skillet until browned and crumbly, 5 to 7 minutes; drain and discard grease.
Mix beef and sausage into bean mixture; season with cumin, garlic salt, and chili powder. Reduce heat to medium low, cover stockpot, and cook chili for 30 minutes more.
