Nichols is expected to sign to play under former coach Ange Postecoglou in Melbourne after the Roar confirmed he was leaving.

The one-time Socceroo's contract expired on April 30 and Roar managing director Sean Dobson said he was disappointed to see the 24-year-old leave.

"We'd like to thank Mitch for his contribution in his six seasons at the club and we wish him well in his future endeavours," Dobson said in a statement.

"We've been in constant communication with Mitch and his management during this season. However, at this time Mitch indicated he feels he needs a new challenge.

"From the club's point of view, we're comfortable knowing we did everything in our power to keep Mitch in Brisbane Roar colours."

Nichols made 125 appearances for Roar, netting 24 goals, while he played a key role in Brisbane's back-to-back A-League championships.

His form dropped off after the departure of Postecoglou at the end of the 2011/12 season, but he looks set to be under his former coach next campaign.

Nichols was at his best under the Victory coach and would put pressure on the under-performing Marcos Flores if he were to join the club.