After spending the 2003 AFL season in the Geelong reserves further developing his game, Mackie made his senior debut in 2004, and picked up a Rising Star Nomination for a three-goal performance.

Despite having played as a midfielder for Glenelg, Geelong attempted to turn Mackie into a key forward to fill a long-standing void, with mixed results.

He continued his solid form for the rest of the season and played a big part in Geelong's hard-fought preliminary final win over Collingwood.

In 2005, a late night incident involving Mackie, his club teammate Steve Johnson and the police was reported by the media.

[3] He was delisted at the end of the 2017 season without having played a game, and subsequently joined Box Hill in the Victorian Football League (VFL).