Strength-training exercises targeting your buttocks really can tone and strengthen those large muscles. That said, butt exercises can't magically reduce any extra fat you have lingering in that area, and you only get as much effort out of strength training as you put into it. If you want to see results, you should strength train at least twice a week, doing progressively more challenging exercises as your capabilities increase.
How to Target Your Butt
In order for a butt workout to really target your glutes, it must include either hip extension -- straightening your leg at the hip, or swinging it back past straight -- or hip abduction -- swinging your leg out to the side. Quite a few cardio exercises provide the type of movement you need, including walking, running, cycling and rowing.
For Better Results
Although most cardio will tone your buttocks at least somewhat, if you want to see more dramatic results you're going to have to strength train. You can do glute-isolating exercises like hip extensions or hip abduction, but you'll get more results faster if you focus on compound exercises that emphasis glute involvement. These include squats, deadlifts, kettlebell swings and Olympic lifts and most of their variations. If you'd rather use butt-targeting machines in the gym, head for the leg press or the butt blaster, which is also sometimes called a mule kick machine.