The 21-year old was unveiled as a Roar player on Monday, marking the first signing of John Aloisi's reign as head coach of the three-time A-League champions.
MacLaren has spent the last two seasons at Perth Glory, scoring 11 goals in 38 matches. He notably scored a hat-trick against Melbourne City in April, and has represented Australia at under 21 and under 23 levels, having previously represented Scotland at under 19 level.
Aloisi was thrilled to have signed the young star from under the noses of several A-League rivals.
"Jamie is one of the most promising young strikers in Australia at the moment," the Roar coach said.
"He is a genuine goal scorer who is leading the way in the qualifying campaign for the Rio Olympics.
"He is an ideal fit for the attacking way I want the Roar to play this season and I can't wait to see him on the field in our Orange."