The 28-year-old singer, who performed her hit track Roar, impressed judges Gary Barlow, Sharon Osbourne, Louis Walsh and Nicole Scherzinger as she belted out her catchy single.
Embracing her wacky outfit, Katy looked incredible and showed off her feminine curves in a tight orange mini dress flanked with a tiger-printed veil.
The American songwriter completed her wild look with a pair of tiger ears, elbow-length gloves and a chunky gold necklace. Katy kept her make-up simple, wearing her trademark red lipstick.
A group of male dancers dressed as businessmen carrying briefcases added to the dramatic stage effect, and whipped off their costumes to reveal animal-patterned metallic jumpsuits.
Katy was clearly delighted to make her X Factor appearance, and certainly owned the stage as she pranced around her dancers.
"I get to dress up like a big cat so I love this song," Katy told show host Dermot O'Leary after her performance. "I feel great."
With Gary, Louis and Sharon reportedly set to leave the X Factor after this series, Dermot asked Katy how she would feel joining the judging panel.
"Oh my goodness, I would love to give constructive criticism," said the singer.
The brunette beauty, who has previously acted as a guest judge on the show, has already proven how competent she would be, as she reminded fans that she put One Direction's Niall Horan through to the next round.
"I like that I let Niall through," said Katy. "He's now in a little band called One Direction."
The elimination process followed her performance, which saw Shelley Smith bidding farewell after her sing-off with boy band Rough Copy.
Sharon added heaps of drama to the results as she pleaded with fellow judge Louis to save her Overs' girl.
"I'll do anything, anything Louis," begged Sharon as she showered him with kisses, to no fine result.
This week's episodes saw more drama than usual, with girl band Miss Dynamix being exempt from performing after the group's pregnant member SeSe Foster was rushed to hospital during rehearsals.