The singer was transformed into a tiger as she belted on the hit on a podium surrounded by dancers dressed in suits.
Flashing the flesh in a tight animal print number, Katy finished off her feline look with a pair of tiger ears.
"I get to dress up like a big cat so I love this song. I feel grrreat!" she told host Dermot O'Leary following her performance.
She also revealed she would be up for returning to the show as a judge, after previously sitting in on some auditions during the 2010 series.
The remark prompted the 1D star to propose marriage to the 'California Gurls' singer.
"I love you @katyperry ! Thank you! Ps . Will u marry me?" he tweeted.
We think Katy's current squeeze John Mayer, might have something to say about that.