The dad-of-three, who was dressed in a black top, was seen getting up close and person as he leaned over the pretty brunette as she laid down next to a pal on an outdoor bed.
Christina - who is signed to Next Models LA - previously joined Scott on a vacation to Mexico earlier this year.
And Scott, who flew into Cannes via private jet, was spotted with Kendall Jenner on Sunday night at Gotham nightclub and again on Monday when they partied together at the Chopard bash.
A source told PEOPLE : "Scott is still very much around. He communicates with all the siblings, and he sees Kourtney a lot. He joins family dinners and is always invited for holidays. He's fun to be around. Plus, he's family."
The insider added: "No matter what happens, he is their dad. The family will always care about Scott because of that. Think what you want about the Kardashians, but they don't shut people out."
While Kourtney’s family have shown their support for Scott, the businessman - who checked himself into rehab last year - has previously been forced to defend his post-split partying.
He said: "The truth is I just to live my life and I want to have a little happiness and a little balance. The truth is rehab did help me and now I'm just trying to be responsible. I'm not out here trying to get wasted, but you know what, I will have a beer on the beach. I'm not doing drugs, I'm not doing anything insane, so I think people just need to relax ... I just want to try to live my life."
"I'm not sure I can stay home every single night at 32 years old and be sane. In the end, I'm trying to live my life. I'm trying to live it healthy. I'm trying to be there for the people I love, which is Kourtney and kids, but you know what, we're not together."
