Place meatballs in a food processor and pulse several times until crumbled, then transfer to a large saucepan.
Add marinara sauce, 1 cup water, and the chili seasoning. Heat mixture to a boil over medium-high heat. Cook 2 minutes.
Stir in all three beans. Bring to a boil, cover, reduce heat, and simmer 10 minutes. Prepare and serve corn muffins, if desired.