Disclosed is a method and apparatus for providing wireless access in a broadband wireless access system. The apparatus authenticates an access terminal when an access of the access terminal located in a first network employing a first predetermined access scheme is detected, allocates a private Internet Protocol (IP) address to the authenticated access terminal, translates the private IP address into a public IP address when an access of the access terminal through the private IP address is detected, and controls that the access terminal accesses a second network employing a second predetermined access scheme through the public IP address.