The 20-year-old agreed new terms on Friday, extending his current deal to keep him at the club until 2015.
Main, who is currently recovering from reconstructive knee surgery, is anxious to build on the opportunity.
"I'm grateful the manager has shown faith in me and I can't wait to restart full training and get playing again," he told the club's official website.
"I've really enjoyed my time here and I hope I can continue to make progress. I realise there is stiff competition for places, but that will only spur me on."
The former Darlington man original penned a one-year deal last summer after an impressive trial spell with Tony Mowbray's side.
Middlesbrough last week