The England Under-21 international, who has featured 14 times for the Magpies this season, will not be eligible to feature in Wednesday's FA Cup tie against Chelsea but an agreement is in place to extend his stay should Boro make it into the Championship play-offs.
Manager Tony Mowbray told the club's official website: "He gives us a different option and more options in an a similar way to Muzzy Carayol.
"He's an out-and-out attacking wide player who can operate on either side and will be ideal when we want to play with two wingers.
"He will hopefully give some players a lift and create some competition."
- Sports & Recreation