All grown up: JoJo leaves her child star past behind with a super-glamorous appearance at NYLON party

She was the slightly precocious teenager who scored a hit single with her debut track Leave (Get Out).

But last night JoJo showed she is all grown up as she attended NYLON Magazine's Young Hollywood Issue celebration ahead of her career comeback.

The 20-year-old singer was virtually unrecognisable as she posed on the red carpet in Los Angeles wearing a tight denim cut-out dress which flattered her slim figure.

Look who's here: JoJo was virtually unrecognisable at the NYLON party in the Bardot nightclub in Los Angeles last night

Who's that girl? A sultry-looking JoJo in denim, a far cry from her child star days, right

And with her hair dyed a more sultry black, JoJo proved she has left her child star days far behind her.

JoJo shot to fame on the TV programme America's Most Talented Kids at the age of 12.

Despite losing the talent contest, she was quickly snapped up by a record label and started working on her debut record, which was released in 2004.

Together again? Peaches Geldof sparks more rumours of a reconciliation as she poses with ex-boyfriend Eli Roth

Short and sharp: Both Paris Hilton and Jordin Sparks chose colourful dresses

Following the success of her first single Leave (Get Out), JoJo continued to enjoy huge success with tracks including Too Little Too Late.

Now, after some time away from the music scene, JoJo is hoping to recreate her previous success with her new album Jumping Trains, due for release later this year.

Talking about the record, JoJo said: 'My third album will be called Jumping Trains and it’s very symbolic for a variety of reasons.

'Moving from Boston to LA, transitioning from being a girl to being a young woman, living on my own, taking a different direction sonically, and just really finding myself and just jumping into a new chapter of life.'

New couple alert? Actress Emma Roberts poses with her co-host for the night, Macaulay Culkin's brother Rory

A Gleeful evening: Glee stars Jenna Ushkowitz and Kevin McHale on the red carpet

JoJo has also been exploring the world of acting, with films under her belt including Aquamarine and RV: Runaway Vacation. She also appeared in the recently remade TV series Hawaii Five-0 earlier this year.

Other stars to attend last night's NYLON event, held at the Bardot nightclub in Los Angeles, included socialite Paris Hilton and actress Emma Roberts.

Peaches Geldof, meanwhile, was there with ex-boyfriend Eli Roth, sparking more rumours that the pair may have rekindled their relationship.

Blondes have more fun: Emma Roberts, right, poses with Hellcats actresses and sisters Alyson (left) and Amanda Michalka

Fashionistas: (Left to right) 90210 star Shenae Grimes, Scream 4 actress Lucy Hale and Robin Williams's actress daughter Zelda

Despite the fact that Geldof is in a relationship with singer Thomas Cohen, she and director Roth looked happy to pose together on the red carpet and even left together.

Geldof tried out a new look at the party as well, opting to tie her hair into a bun and accessorise with a garland of huge flowers.

She teamed the new look with a black and white floral dress and a pair of black sandals.

Close: Sisters Alyson and Amanda Michalka link arms as they walk to their car to head home

Other stars to make an appearance included Glee actors Kevin McHale and Jenna Ushkowitz as well as Scream 4 actress Lucy Hale.

Singer Jordin Sparks, who recently posted a picture of herself showing off her bikini body on Twitter, displayed her newly-slim figure in a ruffled red dress which drew attention to her tiny waist.

Meanwhile, Hellcats star Alyson Michalka arrived at the event with her sister Amanda, who also appears in the hit US cheerleading programme alongside Ashley Tisdale.

As they were: Emma Roberts and JoJo with Sara Paxton in the 2006 movie Aquamarine