 On May 3, 2019, Melville's contract was purchased by the Colorado Rockies, and he was assigned to the Triple-A Albuquerque Isotopes.On August 21, the Rockies selected Melville's contract and promoted him to the major leagues as an emergency starter.In his Rockies debut against the Arizona Diamondbacks, Melville pitched 7 innings and allowed only 1 run on 2 hits as the Rockies won 7-2, giving Melville his first major league win.