In Spencer’s case he takes up an option for 2017 that formed part of his first agreement with the club covering this season.
Oldham head coach Scott Naylor said: “I’m really pleased Jack will be with us again next year. He’s got everything he needs to play at the highest level.
“He’s been very unlucky with injuries this year but, hopefully, he’ll be able to show us in 2017 what a top-class, quality forward he is.”
Spencer played in the first 13 games of the season, which included wins against Dewsbury Rams, Batley Bulldogs, Sheffield Eagles, Hull KR (Challenge Cup) and Featherstone Rovers, a game in which he broke a bone in a hand.
The 25-year old was out for several weeks and in his first game back he suffered a shoulder injury, which again sidelined him for a few weeks before he returned on the bench in Sunday’s impressive 30-8 win at Swinton.
The son of assistant coach Lee Spencer, he has played in 15 of this season’s 28 games in all competitions.