The 'I'm Not Alone' star revealed that he will fly to the US to work on material for Perry's second studio album.
"Katy and I finally met last week at the Capital Summertime Ball. We're gonna record our track in LA in December. It'll be for her next album so we'll be writing it together," Music-News quotes him as saying.
"It would be a shame to go all the way to LA and not meet up with her. It's a long way - we might go out and get on the... milkshakes."
Harris, who produced a remix for Perry's recent single 'Waking Up In Vegas', earlier suggested that the pair will work on a dance song.