Place ground beef and onion in a large saucepan over medium heat; cook and stir until meat is browned and onion is tender, about 5 to 7 minutes.
Stir in tomato sauce, kidney beans, and stewed tomatoes with juice. If you prefer a thinner consistency, you can add water. Season with chili powder, garlic powder, salt, and black pepper. Bring to a boil, reduce heat to low, cover and let simmer for 15 minutes.