The rocker spent months in rehab battling substance abuse and alcohol problems, prompting the group to axe a series of gigs and appearances to promote their album trilogy, Uno! Dos! and Tre! - but Armstrong and his bandmates were back on form for the show at the Fox Theater in Pomona, California.
The two-hour concert was the first of four warm-up shows for the group before Green Day head out to arenas later this month (Mar13).
Fans joined the group onstage, with a very happy Armstrong giving some concert-goers the chance to sing along with him, while one burly devotee hoisted the singer onto his shoulders.
Clearly glad to be back onstage with his bandmates, Armstrong squirted fans with a water gun and hurled toilet paper and T-shirts into the audience.
Covers included AC DC's Highway to Hell, the Isley Brothers' Shout and a brief sample of Ben E. King's Stand By Me, but otherwise it was a fast-paced rip through Green Day hits and new songs from their most recent trilogy release.