"We'd had little falling outs here and there. We'd had some public Twitter spats ... Eight years or so had passed. It was time to put all that behind us," Perry said of her rocky relationship with Harris Wednesday while calling into On Air With Ryan Seacrest.
"We just bumped into each other and he said, 'I think I have a song that maybe you should come check out,'" the pop star said. "I was like, 'Cool,' because we had always meant to work together for years and years and years."
"I came to the studio and he played me a bunch of unfinished but really solid moments for his new record. Then he played me this one part for this new song called 'Feels' and I was like, 'Oh yeah.' This is like my favorite song off the record. I was just down to do it," she said about "Feels."
Perry had previously feuded with Harris on Twitter after the DJ dropped out of the singer's U.K. tour in 2011. Perry has also notably feuded with Harris' ex Taylor Swift and had chimed in on the former couple's spat over Swift stating that she wrote Harris' song with Rihanna, "This Is What You Came For."
"Feels" released in June, also features Pharrell and Big Sean. A music video for the track features the all-star music lineup performing the song while relaxing on a dream-like tropical island filled with sandy beaches and palm trees.
"I'm going to maybe be more the Simon Cowell," she said of acting like the former Idol judge. ""I really respect him. As much as people said, 'Oh, he's grumpy or he's mean,' he was just truthful, you know? He's seen it. I don't need to be there to win the popular race."