An offshore floating support apparatus includes an underwater base, an anchor unit and a plurality of supporting units. The anchor unit is connected to the underwater base and is adapted to be attached to a water bed. The supporting units are connected to and surround the underwater base. Each of the supporting units has a support member that defines a receiving space for receiving water therein and that has a valve component operable to establish fluid communication between the receiving space and external environment for adjusting quantity of water received in the support member.