SYDNEY'S Nick Blakey has signed the longest contract extension in the competition, with the Swans securing their former Academy graduate to a mega seven-year deal that will ensure his future until at least 2031.

Blakey, who was already signed through until the end of next season, added another seven years to his deal this week in a landmark extension that takes the length of his contract past Harry McKay and Clayton Oliver (both signed to 2030) as the AFL's longest.

The 23-year-old wasn't due to become a free agent until 2026, but has signed a deal that goes beyond that and one that will ensure he will now remain in Swans colours until at least the age of 31.

Blakey arrived at Sydney with the 10th pick in the 2018 national draft, having been a graduate of the club's Academy program. His father John, a 359-game player at Fitzroy and North Melbourne, was a former Swans assistant coach throughout his childhood.

The running defender has since played 89 games for the club, forming a key part of the side's backline and enjoying a standout start to this season, where he has averaged a career-high 20.8 disposals and 7.5 intercepts per match.

"Nick is a great young man and a very important part of our young group, so we are delighted that he has chosen to extend his career with the Swans long term," the club's football boss Charlie Gardiner said.

"He has some unique talents on field and has worked incredibly hard to overcome injuries over the past couple of years to turn himself into a high-quality defender and provide enormous flexibility to the team.

"Nick has a very strong connection with the club having come through our Academy program as a talented junior and is a much-loved figure amongst his teammates and our staff. He brings great energy and enthusiasm and I’m sure our fans and supporters will continue to enjoy watching him play in the years ahead."

Blakey joins co-captain Callum Mills (contracted until 2029), Isaac Heeney and Tom Papley (both contracted until 2028) in committing his future to the club long term.

As revealed by AFL.com.au's Inside Trading earlier this year, Sydney has also signed former first-round pick Angus Sheldrick to a contract extension that will ensure his future at the club until 2025.