Kvitova also considered Tomas Berdych as a partner before making her announcement Friday.
Stepanek won his first Grand Slam title at the Australian Open when he and Leander Paes of India took the doubles final.
Kvitova says, "As an experienced doubles player, Radek will be the leader."
Kvitova and Berdych played together in January to give the Czech Republic its second Hopman Cup title.
Berdych has already announced he will play doubles with Stepanek at the London Games.