BBC One has announced that the 'Bad Romance' singer and the jazz legend will grace the Strictly dancefloor on October 19th in one of its highest-profile guest appearances to date.
The duo will sing a track from their new collaborative album 'Cheek to Cheek'.
The official @BBCStrictly Twitter account posted: "Get ready to Cha Cha for Gaga! @ItsTonyBennett and @LadyGaga will be dancing cheek to cheek on Strictly."
The news is likely to leave bosses at ITV rival The X Factor - who are known to go all-out to secure star guests - worried that big names will now flock to Strictly, which continues to thrash it in the ratings war.
If she only does one of the shows, Gaga's decision to switch sides could be seen as a snub, as she's performed on X Factor on three occasions in the past - and its eighth series even featured a 'Queen vs. Lady Gaga' themed week.
Although Gaga and Bennett's jazz music might seem better suited to Strictly, it would also have fit in with X Factor's traditional 'Big Band' week.
Strictly continues tonight on BBC One, with the first X Factor live show airing next weekend.