Brown the ground beef in a skillet over medium heat until fully cooked.
Drain excess fat and transfer the beef to the crock pot.
Add the chopped onion and minced garlic to the crock pot.
Pour in the canned diced tomatoes and their juice.
Add the drained kidney and black beans.
Stir in chili powder, cumin, salt, and pepper.
Mix all ingredients well to combine.
Cover the crock pot and set it to low for 6-8 hours or high for 4 hours.
Stir occasionally if possible for even cooking.
Serve hot, topped with shredded cheddar cheese.