The event features happy hour specials and live entertainment at participating businesses in the Arts District and Boyle Heights.
The festival runs through Sunday, but Saturday will be the only day the bridge will be shut down to traffic.
From 1 p.m. to 9 p.m. Saturday, a main stage on the bridge will feature several live performances, headlined by L.A.-based band Ozomatli.
City officials and community organizations will also break ground on the Sixth Street Park, Arts, and River Connectivity project, which will transform the land beneath the bridge into a park.
Proceeds from the event will support community-driven initiatives in the Arts District and Boyle Heights, officials said.