St Kilda ruckman Rowan Marshall has put pen to paper on a contract extension, signing a three-year deal to remain a Saint.

The 23-year-old has extended his deal until the end of the 2022 season, after announcing himself as the Saints' number one ruck option this season.

Marshall has played nine games so far this season, and averages 16.6 disposals, 26.0 hitouts and 5.2 clearances per game.

“We’re thrilled to have Rowan sign on for a further three years,” Saints List Manager James Gallagher told saints.com.au.

“His performances and the way he has embraced the challenge of his new role this year is reflective of the overall attitude with which he approaches his football.

“He’s a professional, determined and passionate young man, and we believe he has a really exciting future ahead of him here at the club.”

The emerging big man has only played 22 games for the club so far in his career, but is excited to extend his deal and remain a Saint.

“I’ve loved my time at the Saints so far and am stoked to have signed this new deal,” Marshall told the club's website.

“I feel like I’ve really learned a lot during my time, especially the past eight months or so, and I’m excited to keep growing and learning.

“I really believe in what we’re building and I’m looking forward to being part of it.”