Mackintosh started his playing career at a young age with Gala RFC. As he grew older, he was selected for various representative teams, including the Border Reivers Under 16 and Under 18 programs. He parlayed those representative appearances into an opportunity in the Scottish Premiership with his old club, Gala RFC.
With Gala RFC, Mackintosh played in the British and Irish Cup for 2 years. He made the decision to join Hawick RFC shortly after, who also compete in the B&I Cup. His strong play there earned him selection to the South of Scotland representative team. Most recently, Mackintosh has been suiting up for the Currie Chieftains.