The 85-year-old said that he is a long-time fan of the 'You and I' singer's work.
He told MTV News: "My favourite is that Lady GaGa. She's the biggest. I'll tell you, I never met anyone with more talent than that lady."
Bennett also shares a duet with GaGa on his forthcoming Duets II album, performing a rendition of the classic 'The Lady Is A Tramp'.
The singer will also release a 73-disc Complete Collection on November 8 in the US.
Bennett recently led an emotional tribute to Amy Winehouse at this year's MTV Video Music Awards alongside Russell Brand and Bruno Mars.
> Lady GaGa sings 'Happy Birthday' to Tony Bennett - Video
Watch Lady GaGa's new 'Nymph' video for 'You and I' below: