Cook bacon in a large skillet over medium-high heat, turning occasionally, until crisp, about 10 minutes. Drain on paper towels until cool enough to handle, about 5 minutes. Crumble cooked bacon into a small bowl.
Cut broccoli into florets, dice stems, add florets and stems to a large bowl. Stir in onion. Add raisins and Cheddar cheese. Stir in crumbled bacon.
Combine mayonnaise, sugar, and vinegar in a small bowl; pour over broccoli mixture and stir until broccoli is completely coated.
