John Longmire will remain Sydney coach until at least the end of the 2020 AFL season after signing a contract extension.
Longmire was contracted until the end of 2017, but the Swans moved quickly to keep him at the club for a further three years.
Longmire took the senior coaching role in 2011 after nearly a decade as an assistant under Paul Roos.
Since then the 45-year-old ex-North Melbourne player has guided the Swans to the finals every season, along with the 2012 premiership and 2014 grand final.
"There's no question that John's leadership has been a key ingredient in our team's performance - he drives high standards right across the football club," general manager of football Tom Harley said on Tuesday.
"Already this season we have blooded six AFL debutants.
"We firmly believe John is the best person to guide our young players and coach our team as our list and the demands of the competition continue to evolve."