The 26-year-old was traded alongside picks 42, 61 and a future fourth-round pick, while the Hawks have sent back pick 50, and a future second-round pick.
Frost played 70 games for the Demons, with Melbourne’s General Manager of Football Operations Josh Mahoney detailing the reasons for the deal on the club’s website.
“Sam has played an important role for us in his five years at the club after joining from GWS and we thank him for his contribution,” Mahoney told Melbourne Media.
“We were not in the position to offer Sam a long-term contract, so we were comfortable with him exploring his options and we’re pleased he has found a position at Hawthorn.
“It’s always disappointing to see any player leave, but we think Sam will benefit from the move and we are confident in our backline.