HAWTHORN has kept four-time premiership defender Grant Birchall off the free agency market, signing him to a two-year contract extension that keeps him at the club until the end of 2019.

The 28-year-old would have become an unrestricted free agent at the end of next season, but won't be part of the changing of the guard at the Hawks, which started with the high-profile departures at the end of last season of Sam Mitchell and Jordan Lewis.

Birchall is one of the most reliable and durable Hawks and needs 10 more games to play 250 games in the brown and gold.

Recruited from Devonport, many would now regard him as the second greatest Tasmanian to play for the club, behind only Peter Hudson. He played in the 2008, 2013, 2014 and 2015 premiership sides. He earned All Australian selection in 2012.

"Grant is a really important player for us and a vital member of our backline," said Hawthorn list manager Graham Wright.

"He has been a part of this club for over 10 years now and we were really keen to retain him.

"We are really pleased that Grant has signed on for another two seasons and believe he has plenty of good footy ahead of him."

It has been reported Birchall signed the new contract some time ago, with the club waiting to announce the deal after a turbulent trade period that saw fellow veterans Sam Mitchell and Jordan Lewis depart for West Coast and Melbourne respectively.