Breakfast show host Nick Grimshaw just made the announcement on his show this morning.
One Direction said: "We're so excited to perform at Radio 1's Big Weekend in Glasgow. Glasgow we are coming to get you. We're going to put on a great show and we can't wait to see you all there."
Bastille, Jake Bugg, Lily Allen, Ed Sheeran, Coldplay and Pharrell Williams complete the line-up for Saturday, May 24.
Meanwhile, artists confirmed to take to the stage on Sunday, May 25, include Kings of Leon, The Vamps, John Newman, Rita Ora, The 1975, Tinie Tempah, Paolo Nutini and Katy Perry.
Kasabian will also play In Music We Trust stage on the Sunday with more acts announced for this stage on Zane Lowe's Radio1 show tonight at 7pm to 9pm.
All 50,000 tickets for Radio 1's Big Weekend Live from Glasgow Green were given away earlier this month in an incredible 35 minutes.