The 34-year-old Backstreet Boys crooner and 43-year-old New Kids on the Block singer announced the collaboration Wednesday on Good Morning America.
"Me and Nick have combined our talents, our super powers, and now we are a new duo, called Nick & Knight," Knight says. "We recorded a whole new album and we are going on tour September 15."
"We're almost pretty much done with the album," Carter adds. "It's a bunch of our pop, rock, R&B and urban. It's all mixed together to create Nick & Knight."
Nick & Knight is set for release September 2. The duo will then embark on a tour across North America. Carter and Knight previously toured together with their bands as NKOTBSB in 2011-2012.
Nick & Knight's song "Just the Two of Us" is available as a free download for those who preorder the album.