The 19-year-old broke into the first-team squad over the summer and has been rewarded for his progress with improved terms.
A product of the club's Academy, Poleon scored 12 goals in 27 appearances in their U18 side during the 2011/12 season before making the step up, and he also enjoyed a successful loan spell with Bury.
"I'm glad to be tied down and commit my future here," said Poleon. "I know I'm going to be here for a number of years now and I can work to that and hopefully push on.
"When I started the season I was happy to do well and scoring was a bonus.
"The loan was all about me experience and that was a bonus doing well at Bury so it's worked really well.
"I can only thank the gaffer here for the faith he has put in me. I'll keep working hard, and hopefully I can shine and do well."