Boy bands unite!

For the first time ever, New Kids on the Block and the Backstreet Boys shared the stage while performing on Sunday's American Music Awards in L.A.

Dubbing themselves "NKOTBSB," the '90s crooners -- including NKOTB's Donnie Wahlberg, 41, Danny Wood, 41, Joey McIntyre, 37, Jordan Knight, 40, Jonathan Knight, 41, and BSB's Brian Littrell, 35, Nick Carter, 30, A.J. McLean, 32, and Howie Dorough, 37 -- closed the show with a medley of hits (watch above).

The '90s boybands will team up yet again for their NKOTBSB tour, which kicks off June 8 in Toronto.

"We got such a great response," Carter recently told of their longtime fans, who are now all grown-up.

Added Wahlberg: "It's cool to see them bring their kids to our shows and start a new generation of fans again!"