 On December 19, the Coyotes traded Leighton (along with a fourth-round pick in the 2019 NHL Entry Draft) to the Pittsburgh Penguins in exchange for Josh Archibald, Sean Maguire and a seventh-round pick in the 2017 NHL Entry Draft.Leighton entered the 2018–19 season as a free agent.On November 16, 2018, he continued his professional career after signing a professional try-out (PTO) contract with the injury-hit Ontario Reign of the AHL, the top affiliate of the Los Angeles Kings.