The pop star and her reality-TV boyfriend were all over each other at the Premiere nightclub in Hollywood on Tuesday, even with Lavigne's ex-husband, Deryck Whibley, nearby.
Looking like teenagers in love, Lavigne, 26, and Jenner, 27, stole kisses and touches from each other all night, as they partied with friends – including Whibley, 30, who spent time chatting with them at their table.
Jenner seemed uninterested in anyone but his girlfriend, showering her with attention and pulling her in for a kiss whenever he got the chance. Lavigne didn't stray far from Jenner throughout the evening, constantly sitting on his lap and whispering in his ear.
The couple got together in the spring, and have been holding PDA sessions in clubs ever since.