The music duo was spotted on Wednesday night leaving Hollywood hotspot Chateau Marmont, after having dinner together.
The 27-year-old “Wide Awake” singer and John, 34, reportedly enjoyed a romantic meal that included hand-holding, kissing and lots of laughs, Us Every week reported.
“They’re hooking up right now,” the source said. “It’s not serious ” yet!”
A source told the journal that the duo is basically having fun at the moment.
The Chateau Marmont fireworks come on the heels of a reported date on June 19 at Soho House in West Hollywood.
“They were affectionate, holding hands and cuddling,” an Us Every week source said of their June date.
Katy finalized her divorce form Russell Brand in February.
John has been linked to a slew of Hollywood beauties over the years, including Jennifer Aniston, Jennifer Love Hewitt and Jessica Simpson.