Naismith missed all of this season after suffering an anterior cruciate ligament injury in early March.

The 205cm ruckman was picked up by Sydney in the 2013 rookie draft and played the first of his 28 games in 2014.

He was part of their losing grand final team in 2016.

It's the second time Sydney have extended the 26-year-old Naismith's contract following a season he didn't play a senior game in, as was the case following the 2015 campaign.

"It shows that the club really wants me here and it's a show of faith that they see me here long-term," Naismith told SwansTV.

"That's a really good incentive for me to push myself and really repay the faith.

"My pre-season's pretty much started. I''m ready to get stuck in and hopefully when we come back, I'm a few steps ahead of everyone."

Australian Associated Press