Gunston was initially contracted until the end of the 2019 season, however his new deal will now take him through until the end of 2022.
“It’s exciting for the club to have Jack’s future secured for a further four years,” Hawthorn’s GM of Football Graham Wright told hawthornfc.com.au.
“Jack has become a vital part of our team since joining us at the end of the 2011 season and has had a fantastic home and away season this year.
“Jack’s an important member of our leadership group and at just 26, we feel he has some of his best footy still ahead of him.”
Gunston has played 155 games for the Hawks since joining the club at the start of the 2012 season.