Gresham, 19, impressed in 2016 – playing 18 games and kicking 11 goals as a goal-sneak in his first year in the AFL.

Taken by St Kilda at pick 18 in the 2015 draft, Gresham became a regular in the Saints forward line, complementing talls Josh Bruce, Tim Membrey, Paddy McCartin and Nick Riewoldt.

He earned particular plaudits in round 14 after snapping a crucial goal at a pivotal stage of the Saints' clash with Geelong, helping his side to an upset victory, and in doing so earning himself a Rising Star award nomination.

Gresham said he was glad to recommit to the club. "I'm really happy to get the contract out of the way and sign for another two years at St Kilda," Gresham told the club's website.

"I've loved my time here so far, love being around the club and the boys. I've made some really close mates already, so I'm looking forward to the next few years and what the future holds.

"Coming into my first year at the club, I didn't expect too much; I just wanted to earn respect off all the boys and the coaching staff. So to play most of the season I was pretty happy with that. I'm really looking to build on this season in 2017 and improve."

The Victorian – who was recently given the vacant No. 4 jumper at the Saints, worn by club greats Tony Lockett, Darrel Baldock and Barry Breen – said he was hoping to improve his endurance ahead of next season.

"My main focus this pre-season is building my tank so I can hopefully spend more time in the midfield next season if the opportunity comes up. I'm also just looking to improve all aspects of my game so I can hopefully cement my spot in the side next season."

The Saints chose Gresham with a pick they obtained in a three-way trade with Sydney and Essendon, in which the Saints relinquished pick five and gained Jake Carlisle.

St Kilda chief operating officer Ameet Bains said he was happy the Saints had worked to ensure they kept a first-round pick in that trade.

"Whilst achieving that didn't guarantee the player we could then draft, it gave us an opportunity to bring an elite young talent to the club in the first round," Bains said. "On reflection, we are pleased that we were able to bring Jade to the Saints."

Gresham's extension follows that of Membrey – who also signed with the Saints until the end of 2019. Having risen to ninth in 2016, the Saints are targeting their first finals berth since 2011 next year, while also looking to continue their off-field revival, aiming for 31,000 members by the end of 2016.