The actor was treated for an addiction to prescription pills earlier this year, but booze wasn't off the menu when he hit the three day-long music event along with a flock of other Hollywood stars.
Witnesses say the 42-year-old was drinking throughout the day on Saturday, topping off the evening by befriending an unnamed brunette on the dance floor.
"The two were grinding like they were at a middle school dance," a fellow festival goer told Page Six. "He didn't seem to care who was watching."
After wooing his new ladyfriend with his dance skills, Gerard escorted her off to the portaloos for some quiet time.
Radar Online reports that the actor "partied like crazy" at the music festival. "He looked totally dishevelled at one point and he looked like he was drinking whiskey," a witness told the website.
"He appeared unsteady on his feet and was dancing like a crazy guy. He looked wasted."
Check out who else was at Coachella...