Brown the meat in a large non-stick skillet with diced onion over medium-high heat, breaking the meat into small pieces until fully cooked. Add minced garlic during the last minute of cooking.
Remove the cooked meat mixture from heat, drain excess grease if necessary, and transfer to the slow cooker.
Add crushed tomatoes and diced tomatoes to the slow cooker. Stir in Worcestershire Sauce and chili seasoning.
Add rinsed dark red kidney beans and light red kidney beans to the slow cooker and mix well.
Cover the slow cooker and set it on low heat for 8-10 hours or high heat for 4-5 hours.
Serve hot with optional toppings like cheese, sour cream, chips, or cornbread.