Kevin Richardson to Re-Join the Backstreet Boys

Kevin Richardson attends "The Casserole Club" premiere n August 25, 2011 in Hollywood. David Livingston/Getty

Backstreet's back…to being a quintet!

After parting ways with the Backstreet Boys in 2006, Kevin Richardson, the group's eldest original member, is slated to make his much-anticipated return.

"Now everything is back to normal…welcome back Kevin Richardson," the group, including members Brian Littrell, Nick Carter, Howie Dorough and AJ McLean, tweeted Sunday from their official account.

The foursome originally made the announcement earlier that evening on stage during their concert at London's O2 Arena.

"I think we should let them in on the secret that we have. Since we love you guys so much, we are going to be back this year," said Carter.

"And Kevin is coming back!" Littrell, who is Richardson's first cousin, interjected to cheering fans.

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Brian Littrell, AJ McLean, Nick Carter and Howie Dorough of the Backstreet Boys perform on NBC's "Today" at Rockefeller Center on June 3, 2011 in New York City. Jemal Countess/Getty

Later, Richardson, 40, who has since made sporadic appearances with his group mates through the years, confirmed the news via his Twitter account.

"Hello beau-ti-ful people. Yes, the cat is OFFICIALLY out of the bag. It's on and cracking!" the singer tweeted early Monday morning.

The Kentucky native, who has dabbled in acting, music producing and a solo career since his BSB exit, last appeared on stage with the group at the Staples Center in Los Angeles July 1, 2011. He joined in on their hit "I Want It That Way" during the concert's finale, which also included New Kids on the Block members Donnie Wahlberg, Danny Wood, Joey McIntyre, Jordan Knight and Jonathan Knight. (The two iconic boy bands, dubbed NKOTBSB for short, did a joint tour that year.)

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New Kids On The Block and the Backstreet Boys perform in concert together on June 8, 2011 in Toronto. George Pimentel/WireImage.com

Richardson's return isn't the only announcement worth celebrating in BSB land — McLean revealed via YouTube Sunday that he and his wife of four months are expecting their first child together.

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