A bustier (alternately bustiere) is an article of clothing for women, which is form-fitting and is traditionally worn as lingerie. It looks somewhat like a Basque, but a bustier is shorter. It reaches down only to the ribs or the waist and has a different function: its primary purpose is to push up the bust by tightening against the upper midriff and forcing the breasts to move up, while gently shaping the waist. Modern bustier are often made with mesh panels rather than boning. The bustier is a multi-purpose garment and doubles up as a push-up bra for inner wear and as a camisole for outer wear. The bustier can also be worn as a half-slip under diaphanous upper garments if a bold display of the midriff is not desired.

In modern days, women wear a bustier as an undergarment/push up bra in the occasion that their dress or outer-wear has a low-back.