A post on the American Idol host's official website has announced that the two bands will join forces for a concert tour across the US from next summer.
All members of both bands will appear on Seacrest's KIIS-FM radio show on November 8 to reveal further details about the production. They will also perform together at the American Music Awards on November 21 on ABC.
A subsequent post on the Backstreet Boys official Twitter feed directed at the New Kids On The Block account read: "This is gonna get CRAZY! Fasten ur seat belts boys we are going on a ride! (sic)"
Rumours that the bands were preparing for a joint venture first surfaced back in August.