Jonathan Brown has announced his retirement, effective immediately.

Brown announced his decision at a media conference along with coach Justin Leppitsch and football director Leigh Matthews on Monday afternoon.

Speculation had mounted that the 32-year-old would call a halt to his glittering 15-year career after being carried off with concussion against Greater Western Sydney in round 13.

Brown played 256 games, won three premierships and kicked 594 goals.

The retirement of their inspirational captain will provide even further motivation for a Lions' side coming off a disappointing loss against Fremantle.

Brisbane had just 17 inside 50's against the Dockers, a record-low since stats have been recorded.

North has already played Leppitsch's team once this season, with an 87-point victory in Round 9 its best of the season.