Place a large pot over medium-high heat. Add the ground beef and cook, breaking it apart with a spoon, until browned and no longer pink. Drain excess fat if needed.
Add the diced onion and cook for 3 to 4 minutes until softened.
Stir in the drained kidney beans.
Pour in the pasta sauce and fill the empty sauce jar with water, then add that to the pot.
Sprinkle in the chili seasoning and stir everything together until well combined.
Bring the mixture to a gentle boil. Reduce the heat to medium-low and simmer uncovered for 10 minutes.
Stir occasionally to prevent sticking. Continue cooking for another 15 to 20 minutes until the chili thickens and the flavors blend together.
Taste and adjust seasoning if needed. Serve hot with shredded cheese, sour cream, crusty bread, rice, or tortilla chips.
