And at the Viper Room of all places! Here's a super slim Kelly Osbourne (sporting some longer blonde locks) walking arm-in-arm with Pussycat Dolls founder Robin Antin into the venue Wednesday night...

Kelly also took to Twitter before and after her performance, even posting the below pic of herself in a sexy black bra!

kellyosbournebra.jpgPhoto courtesy of Twitter

Werk it, girl.