The photo appeared moments before it was officially confirmed that the 'Toxic' singer has joined the judging panel for the Fox talent competition.
Spears has been rumoured to be joining the show, along with Demi Lovato - but no official announcement has yet to be made.
Simon Cowell also tweeted the photo, saying: "Can't believe it's finally happened. Very exciting!"
Fox is expected to officially announce the lineup for the second season of The X Factor during its upfront presentation today (May 14).