JoJo heated up Hollywood last night, attending back-to-back parties and turning heads at both. The 20-year-old singer was looking grown and sexy in a black skirt and sheer top while baring her toned legs at the IZOD party to celebrate the 100th Anniversary Indianapolis 500.

She then changed into a form-fitting white number and raced over to the launch of former “Hills” star Audrina’s new VH1 reality show at The Redbury Hotel, partying with Christina Milian and Rob Kardashian.

JoJo’s first album for Interscope Records is done and awaiting a release date. A video for the lead single will be shot soon.

LOS ANGELES, CA – APRIL 13: Singer JoJo takes part in a celebration for the Indy 500 100th anniversary at an IZOD party at The Colony on April 13, 2011 in Los Angeles. The Indy 500 will take place on May 29, 2011 at the Indianapolis Motor Speedway.