Heat a large skillet over medium-high heat. Cook and stir beef and onion in the hot skillet until browned and crumbly, 5 to 7 minutes; drain and discard grease.
Mix black beans, diced tomatoes, and sweet corn into beef mixture; add chili seasoning mix, cumin, chili powder, and salt and mix well. Bring liquid to a boil; reduce heat and simmer until chili is cooked through and flavors have combined, about 30 minutes.
