An apparatus and method for supporting Peer-to-Peer (P2P) communications in a broadband wireless communication system are provided. A frame used by the terminal in P2P communications includes a plurality of P2P contention channels overlapping with a region for cellular communications and at least one P2P dedicated channel allocated by a base station only for the P2P communications. The method includes establishing a P2P connection with a correspondent terminal through the at least one P2P dedicated channel, and exchanging P2P communication data with the correspondent terminal through at least one of the plurality of P2P contention channels.