 As a free agent, MacDonald opted to leave the Devils organization and sign his first NHL contract in agreeing to a two-year, two-way contract with the Florida Panthers on July 3, 2018.After attending the Panthers 2018 training camp, MacDonald impressed to make Florida's roster for the 2018–19 season.He made his NHL debut on opening night, and scored on just his third shift, and first career shot in a 2–1 shootout defeat to the Tampa Bay Lightning on October 6, 2018.