The 22-year-old singer recently flew private jet to Las Vegas to be with the star at the weekend, reported Sun Online.
Recently, Harris, 29, posted a photo of Ora boarding his jet and captioned the photograph "You again!"
"They are having a great time and are really into each other," said a source.
She was first snapped with Grammy-winning dance producer at the Brit Awards in February.
"It's early days, but they're keen on each other," the source added.
Ora had a bitter break-up with Kim Kardashian's brother Rob last December who publicly accused her of cheating.