In photos from Sunday, the star, who reached a divorce settlement with Russell Brand in February, packed on the PDA with the tattooed British rocker as they took in the shows: Hugging, holding hands and kissing in the audience.
A source told Life & Style magazine: "Backstage at the Artist Lounge at Coachella last weekend, Katy kept saying her boyfriend was the guitar player for Florence + the Machine.
"She and a bunch of friends were supposed to go see Dr. Dre together, but Katy said she was waiting to watch her boyfriend perform."
The pair were photographed holding hands whilst watching Rihanna perform with Calvin Harris, and Robert later appeared to refer to Katy by her initials on twitter.
He wrote: "Best Coachella ever. Scratch that, best weekend ever. Dre, Snoop, Pac, Nate, Fiddy & KP."
The 'Hot and Cold' hitmaker has previously been linked with Chanel model Baptiste Giabiconi, while her soon-to-be ex-husband Russell – who insists he is “doing well” following the collapse of their marriage - has already moved on with model Nikolett Barabas.
Talking about his positive attitude to the split, Russell recently explained: "I don't have to let anything go. I don't hold on to anything negative. It's the same as zero-ness.
"It's not about letting it go. You can't let go of something you don't hold, you know. It's meaningless, [and] much of our world is predicated on meaninglessness. And I don't do that anymore."