The Best Song Ever hitmaker jetted off to Los Angeles to reportedly enjoy the new year celebrations with Jenner, 18, and her family, and they were subsequently snapped at the Mammoth Mountain Ski resort in California.
A source tells Britain's The Sun newspaper, "Harry was a hit with the family and is spending some time in the States before getting back to work with the band."
The British pop hunk first sparked the romance rumours in November (13) when he was snapped leaving a Los Angeles restaurant with Jenner.
He played coy when Tv personality Piers Morgan recently asked whether the pair is dating, telling him, "We just went out to dinner so no... I guess. I don't know."