Backstreet Boys star A.J. Mclean has married his longtime girlfriend at a ceremony in Los Angeles, after initially postponing the nuptials for a stint in rehab earlier this year.

The singer proposed to girlfriend Rochelle Deanna Karidis while he was celebrating his 32nd birthday in a Las Vegas nightclub in January last year.

They initially planned to marry in May, but McLean checked into rehab earlier this year to seek treatment "for personal reasons", causing them to delay the wedding.

But the pair has now exchanged vows in front of stars including singer Joey McIntyre, comedienne Kathy Griffin and McLean's Backstreet Boys bandmates Kevin Richardson, Howie Dorough and Nick Carter on Saturday.

Taking to Twitter.com ahead of the wedding, McLean wrote, "Wedding is tomorrow, Ro and I could barely sleep last night, I think we're a little excited!"