Scott Disick and Sofia Richie are "officially" hooking up.

The 'Keeping Up With The Kardashians' star and the 19-year-old model are reportedly more than friends, despite Sofia previously insisting they are just pals.

A source told Us Weekly magazine: "Things became official over the past week while they were in New York City together ...

"It's so weird. Not just the age difference, but mostly the fact that Sofia had been a family friend for years, and was close to Kendall and Kylie [Jenner]."

And Sofia is said to be "smitten" with Scott.

An insider said previously: "Since returning to LA, Scott and Sofia are inseparable. They are spending every day together. Sofia seems smitten. It's obvious that she looks up to Scott. She constantly giggles around him. They are very flirty. Scott takes care of her, opens the car door and pays for everything."

Back in June, Sofia had insisted the pair were just friends.

She wrote on Twitter: "The last time I'm gonna say it. Scott and I are just friends. I'm single and focused on friends, family and work. #againrelax (sic)"

And in another tweet, she added: "Just so everyone can get their panties out of their a**es, Scott and I are just homies #relax (sic)"

Meanwhile, Scott's former partner Kourtney Kardashian is confident their children - Mason, seven, Penelope, five, and Reign, two - will provide the "motivation" for him to get his life back on track.

A source said: "She wants her kids to have a relationship with him. She hopes that by allowing him to see the kids, it will motivate him. The kids are the best possible influence on Scott. When is on dad duty and takes them to the movies or out to lunch, he is at his best."