MMAFighting.com was the first to report the possibility of the bout on Thursday, and Heavy.com confirmed the bout with sources close to the event on Thursday afternoon.
Ortiz last entered the Octagon against Forrest Griffin last November, where he lost via decision. He has not won a fight since Oct. 2006. The former light heavyweight champion was scheduled to face Chuck Liddell at the end of the 11th season of The Ultimate Fighter, but a neck injury forced him to withdraw from the bout and undergo surgery.
Hamill faced Keith Jardine in June, earning a majority decision. Ortiz is something of a mentor to Hamill, having coached him on The Ultimate Fighter. The pair remained close after the show concluded.