03/15/2012 AT 5:55 AM ET
The Sum41 rocker came out to the JustFabulous party at the Viper Room, and even shared a hug with Lavigne, who reportedly split from her boyfriend Brody Jenner in January. Whibley also posed for pictures at the event and congratulated Lavigne on her hard work.
And Lavigne wasn’t simply enjoying her party: she performed a set packed with her hits (including “Girlfriend” and “My Happy Ending”) for a packed house, which included Taylor Momsen, Mena Suvari and Kimora Lee Simmons, who introduced the rocker before her performance. (The concert was also streamed live on the Internet for fans who couldn’t make it.)