It's easy to see why Simon Cowell was eager to add Britney Spears to his panel of X Factor judges.
The "Toxic" singer, 30, officially announced her participation in the show during the FOX Upfront event in New York City Monday. Spears slipped into a nude Stop Staring mini-dress (by designer Alicia Estrada) and Giuseppe Zanotti shoes to join Cowell, 52, L.A. Reid, 55, and new judge Demi Lovato, 19, on stage.
Spears -- engaged to Jason Trawick, 40, since December -- changed into another sexy number backstage, opting for a purple Alexander Wang mini-dress. "I couldn't be more excited to join The X Factor judging panel. I'm a huge fan of the show and now I get to be a part of the action," she told Us Weekly in a statement Monday. "Simon and L.A. better watch out!"
Also on display: Spears' 3-carat Neil Lane engagement ring, worth an estimated $90,000!
Spears and Lovato have replaced former judges Paula Abdul, 49, and Nicole Scherzinger, 33, who were fired from The X Factor in January. Ex-host Steve Jones' replacement has yet to be announced.