The 'Clown' singer-songwriter hailed the 'Roar' hit-maker as ''awesome'' after a recent trip to US where she hit the studio with the star to pen a track for her upcoming fourth studio album 'Prism'.
Emeli told The Sun newspaper: ''I've written a song for Katy Perry's album. We did a session together in New York. She was awesome, she knows what she's doing.''
The BRIT Award winner - whose writing credits include Alicia Keys 2012 hit 'Brand New Me' - may also feature on Britney Spears comeback album after contributing a song she wrote with UK hit-maker Naughty Boy.
Speaking of her work on the eagerly awaited follow up to Britney's 2011 album 'Femme Fatale', she said: ''Me and Naughty Boy did the Britney song and sent it off. It's fun writing for an icon and being Britney for the day.''
The novel's author saw a cut of the film and loved each of the changes the movie's director had made.