The 'Last Friday Night' singer greeted fans at The Grove just before her new film was due to begin, telling those in attendance: "You guys are all so cute, even all the way to the back."
An eye-witness told People: "Little girls rushed the screen as Katy walked around slapping hands and greeting fans.
"She managed to sign some autographs and pose for a few pictures before trying to disperse the massive crowd that had gathered around her."
Perry apparently spent 15 minutes meeting with her fans, before joining them to watch the opening portion of her new documentary.
The 27-year-old star's documentary features exclusive performance clips from her 'California Dreams Tour'.
Perry previously revealed that Part of Me also includes a "tasteful" mention of her divorce from Russell Brand.
Katy Perry: Part of Me opens in cinemas on July 5.
Watch a trailer for Katy Perry: Part of Me below: