Gather all your ingredients and chop the onion finely. Drain and rinse the kidney beans.

Optional: Brown the ground beef and onion in a skillet over medium heat.

Transfer the mixture to the slow cooker and add the kidney beans, diced tomatoes, and chili seasoning. Gently stir to combine.

Cover the crockpot and set it to low for 6-8 hours or high for 3-4 hours.

Once cooked, check the consistency and serve hot with your favorite toppings.