The music icon revealed the news ahead of Sunday's headline performance.
The Tony Bennett/Lady Gaga love affair continues, as the pair will celebrate the New Year together.
Lady Gaga is set to join Tony Bennett for a New Year performance at The Cosmopolitan Casino in Las Vegas.
"I can't wait to kick off 2015 'cheek to cheek' with the legendary Mr. Tony Bennett," Gaga said. "New Year's celebrations are about cherishing family, friendship, and the future - three things this man has taught me much about."
Tickets are set to go on sale Friday, 10 October.
Bennett has spoken previously of his admiration for Gaga.
"Nobody has communicated with the public more than Lady Gaga. Ever," he told a magazine.
"I trust the audience, and I'm very impressed. As far as they're concerned, she's part of their family. The only guy who ever did that was Bing Crosby , years ago."
Watch Tony Bennett and Lady Gaga perform I Can't Give You Anything But Love: