Bennett and Underwood will play themselves as they perform at a fundraiser attended by series characters Frank Reagan and Erin Reagan-Boyle, played by Tom Selleck and Bridget Moynahan.
The singers will perform a duet of "It Had to Be You" on the Sept. 23 episode of the show. They initially collaborated on the classic pop standard for Bennett's new album, "Duets II," due out on Sept. 20.
"Having musical legend Tony Bennett and the hugely talented country music star Carrie Underwood perform on our show is a true gift. The talent that they bring together is amazing," "Blue Bloods" Executive Producer Leonard Goldberg said in a statement.
"We're looking forward to an exciting second season premiere with a story that is certain to provoke debate, and are thrilled that Tony and Carrie can be a part of it."