Longmire led the Swans to a flag in his second year in the Harbour City before grand final appearances in 2014, 2016 and 2022 to see the former Sydney assistant enjoy a prolonged period of finals action.
Sydney have featured in September in all but two seasons under Longmire, with the 1990 Coleman Medal winner managing 12 wins and as many losses as coach in finals.
The 52-year-old led a youthful Sydney outfit to the season decider last year, just two years after finishing 16th following plans to rebuild their list.
Longmire, who linked up with the Swans in 2002 under Roos, is now set to see his stint with the club move into 2025 after penning a new deal ahead of the new season's start.
“It's a privilege to continue to be the coach of this great club. I'm lucky to have great people around me, great staff, and a fantastic young playing group,” Longmire said.
“It's exciting to work with young players on their way through to help them learn and grow, while I'm also fortunate to work with quality leaders who take pride in passing on their own experience.
“Everyone at our club is excited, not only about the 2023 season ahead, but about the journey we're on and the opportunity we have before us. We're committed to getting better every day.”
Longmire has coached the Swans in 283 games, amassing 177 wins, 2 draws and 104 losses during his tenure.
Should all go to plan, Longmire will bring up his 300th game in the Swans' box when Sydney host the Western Bulldogs at the SCG in Round 18.
“John has been a fantastic leader of our football club for a very long time, and we are pleased he will continue in his role for at least a few more seasons,” Swans CEO Tom Harley said.
“We believe we have a strong young list, and John has a unique ability to form relationships with our players, which is particularly important with our emerging group.
“With the move to our new home and our leaders locked in it's an exciting time to be part of our club, so I would encourage all Sydney Swans fans to join us on the journey this year.”