QPR have signed defender James Perch from Wigan Athletic for an undisclosed fee.
Theo Walcott and Santi Cazorla have both signed new contracts at Arsenal.
This season Tello has made 16 appearances in all competitions for Barca, having represented Spain at this summer's Olympics.
A Barcelona statement read: "Barcelona announce they have reached an agreement with the player Cristian Tello to extend his contract until June 30, 2016. His buy-out clause has been set at 10 million euros.
"The player will sign his contract on Monday, December 17, in the Barcelona offices."