Combine beef and onion in a large, deep skillet over medium-high heat; cook and stir until beef is browned and onion is soft, about 10 minutes. Drain excess grease.
Stir water, Spanish rice mix, and chili seasoning into the skillet; mix well to combine. Bring to a boil; reduce heat to medium and simmer, covered, until rice is tender, about 7 minutes. Pour in tomato sauce, kidney beans, corn, and salsa; cook until heated through, about 5 minutes.
