The 31-year-old "Dark Horse" singer posted the first photo of the pair, after they attended the star-studded amfAR Cannes Cinema Against AIDS gala, reported US magazine.
Dressed in white robes, Perry, 31, and Bloom, 39, sprawled out on the steps of a hotel for a snapshot she captioned "We Cannes't."
"They're full speed ahead. They're so into each other," a source said.
Earlier this week, they duo was spotted cuddling up on a boat ride and lunched with their famous pals, Kate Hudson and Kate Moss.