The two first enjoyed part of their night with some pals at the Chiltern Firehouse.
After that, the actresses stopped by the Laylow club in Notting Hill. The pair then returned to a party at Chiltern Firehouse, where they didn't leave until 6 a.m.
The Pretty Little Liars star turned 29 on December 18 and the girls were celebrating the big B-Day in the U.K.
A source told Us Weekly that the lovebirds were seeing each other. "Ashley and Cara are dating. This is the first girl she’s ever dated,” the insider revealed.
"The relationship with Cara is the first time she’s been in a healthy relationship and she feels as if it’s really easy with her," the source said about Ashley. The model and the Spring Breakers star met on the set of their film, Her Smell and were spotted smooching at Heathrow Airport earlier this year.
Do you like Ashley and Cara as a couple? Sound off in the comments below!