SYDNEY has locked away another of its brightest young guns after Callum Mills re-signed with the club for a further five years. 

Mills, the 2016 NAB AFL Rising Star winner, had already extended his first contract with the Swans until the end of next season, but has followed that up with a new deal that will keep him in Sydney until at least the end of 2023. 

It comes after fellow Swans academy graduate Isaac Heeney penned his own five-year contract with Sydney in December.

Mills was a standout in defence in his debut season last year, averaging 18.6 possessions across his 22 games, and played with a temperament well beyond his years, in the competition's most miserly backline. 

"It was a really easy decision, the club put so much time and effort into me as a 13-year-old boy in the academy," he said.

"Then to walk into the club a year ago it's seriously exciting, it's a great time to be part of it, and I love everything this footy club is about.

"We've got a bright future that’s for sure, there's a lot of great kids coming through, and I can't wait to repay the club with a lot of hard work, and hopefully some premierships.

"It's good to get it out of the way before round one and focus on the job at hand.

"We're looking forward to playing Port Adelaide and hopefully it's a sellout."

Despite his form in 2016 and some outstanding footy in this year's JLT Community Series, Mills refuses to accept he's a permanent fixture in John Longmire's side.

The soon-to-be 20-year-old joined current teammate Dan Hannebery (2009) and Brownlow medallist Adam Goodes (1999) as Rising Star winners from the Swans, and said he plans to maintain his work ethic this year as the team strives to go one better than last year's Grand Final loss to the Western Bulldogs.

"You can never really feel cemented in the senior side because that’s when someone comes in and takes over (your spot), so I've just got to keep working hard every day and pushing myself," he said. 

"This pre-season has been more solid than last year, I've probably done double the amount of work. 

"It's definitely been harder but hopefully that puts me in the best shape possible coming into the season, which is the main goal."