The film, which was helmed by Knightley's Atonement director Joe Wright, sees the actress don a sheer gown and dramatic smokey eye makeup.
She catches a man's eye, but perform a seductive disappearing act, before appearing behind the wheel of a speed boat.
The print version of the ad campaign, which will hit magazines in April, was shot by Mario Testino.
Watch the new Coco Mademoiselle film below.
Check out Keira Knightley speaking about the Chanel advert here.