Part of busy Santa Monica Boulevard was closed off for the bash, which coincided with the possible apocalypse based on the ancient Mayan calendar.
"If you have to go, you might as well go partying," Warren, 54, of Van Nuys, told the Los Angeles Times.
"I told my friends and family that I loved them, just in case," Warren said. "You just never know."
The run-up to the end of the world likely resulted in nothing worse than, perhaps, some headaches from the loud dance music from the event, which was organized by the city and the West Hollywood Chamber of Commerce.
The scene included go-go dancers and disco lighting, the Times said.
"This city can find any excuse to have a party, and tonight it was the end of the world," participant Michael Arrigo said.
Theater accidentally screens 'Nymphomaniac' trailer instead of Disney's 'Frozen'
Man behind Doritos Locos Tacos passed away on Thanksgiving