was rocking a new look for their guest appearance with Wednesday in .
The 27-year-old flaunted their trim abs in a pair of low cut skin tight leather pants and a crop top reading Corporate Rock Wh*re.
The Billboard Music Award winner was also sporting a new short hair style when they took the stage with the rapper turned rocker to perform a duet of Forget Me Too.
Rockin': Halsey,27, was rocking Wednesday night in Los Angeles, displaying her trim abs in a pair of skin tight leather pants and a crop top at the Machine Gun Kelly concert
Earlier in the evening, the Without Me artist debuted a new look in a quick video on Instagram.
Their long blonde locks had been cut short to reveal what they called the 'return of my mullet.'
The So Good singer also showed off their makeup for the night from their About Face Beauty line, calling it 'the nineties-vibes-only red and blue makeup combo. made by color mixing eye paints and lip paints.'
Duet: The award winning singer performed the duet Forget Me Too with the rapper-turned-rocker at the star-studded event
Guest artists: The So Good singer was one of several guests artists which included Lil Wayne, Blackbear, Avril Levigne and Travis Barker in his first performance since being hospitalized for pancreatitis
The American Music Award winner was not the only guest performer at the star-studded MGK show on his Mainstream Sellout Tour.
Other artists to share their talents at the Kia Forum were Lil Wayne, 39, Blackbear, 31, Avril Levigne, 37 and a surprise guest, Travis Barker, 46.
It was the drummer's first performance since being hospitalized for pancreatitis last month.
New do: Before heading to the concert, Halsey debuted her new short hair style
Mullet: The Without Me singer artist called their new style the 'return of my mullet.' They chopped off her long blonde locks to create the chic new look
The Blink-182 rocker performed two songs, Tickets to My Downfall and Bloody Valentine. Travis' wife, Kourtney Kardashian, 43, was in the wings to support her new husband, seen standing close to MGK's fiancée' Megan Fox, 36.
Halsey is auctioning off a series of paintings created on stage during their Love and Power Tour.
The pieces are expected to go for five to seven thousand dollars each and proceeds will be donated to the National Network of Abortion Funds. The auction wraps up at Sotheby’s Contemporary Discoveries in New York July 19.