The 34-year-old ex of Kourtney Kardashian and the 19-year-old daughter of Lionel Richie celebrated the holiday by attending a party with several other celebrity guests, including newly engaged couple Paris Hilton and Chris Zylka, Rita Ora, and Real Housewives stars Bethenny Frankel and Kyle Richards.
"Sofia and Paris hung out for a lot of the night with Paris' cousins," a source told E! News, adding that the ladies danced and snapped photos in the photo booth.
At the stroke of midnight, Scott gave Sofia a "long kiss," the insider said. The source said the two then enjoyed a fireworks display and did a little dancing before heading home in their SUV.