Gwen Stefani Surprises Audience, Sings 'Hollaback Girl' with Pharrell at Hollywood Bowl - Watch Now!

Gwen Stefani exits through the backdoor at the Hollywood Bowl after making a surprise appearance on stage during the Bruno Mars concert with Pharrell Williams on Saturday evening (May 31) in Hollywood.

The 44-year-old No Doubt rocker performed her hit “Hollaback Girl” alongside Pharrell. Watch the video below!

Also at the Hollywood Bowl for the big concert was Jessica Alba and her husband Cash Warren!

The day before, Gwen visited her acupuncturist for a quick visit and tune up.

FYI: Gwen is wearing Paige Denim overalls on both days.

15+ pictures inside of Gwen Stefani at the Hollywood Bowl…