The Roar hitmaker was in the audience for Cyrus' Bangerz tour stop at the city's Staples Center and she managed to grab the singer's attention from the front row, prompting the 21 year old to take a seat at the front of the stage and reach down to give Perry an intimate kiss on the lips.
The smooch was captured on camera and on video, and after the lip-lock, Cyrus quoted the lyrics to her pal's hit and told the audience, "I just kissed a girl and I really liked it a lot."
Perry posted a picture of the aftermath on her Twitter.com page in a snap showing Cyrus opened-mouthed with shock after her celebrity fan turns away from her. In the accompanying caption, she wrote, "And after (the kiss)! I adore you Miley Cyrus."
Cyrus' show at the Staples Center also featured another surprise for fans as the singer brought out The Flaming Lips stars Wayne Coyne and Steven Drozd to perform their 2002 track Yoshimi Battles The Pink Robots Part 1.
The former child star was so impressed with the onstage collaboration, she asked the rockers to perform it with her twice.