Democratic candidate for lieutenant governor Gavin Newsom was also at the rally.
"We've got to move away from who's to blame and start focusing on what to do," he said.
Earlier in the day in Compton, Brown's message was California is a wealthy state that should spend more money on its least powerful residents.
"We have the potential," Brown said. "We've got to make sure everybody has got an opportunity. Not just the few that suck it up to the top, but we've got to spread it out to everybody so we all enjoy the American dream."
Brown's opponent, Republican Meg Whitman, did not campaign Sunday.
Meantime, Republican Carly Fiorina, who is hoping to unseat Boxer, greeted her supporters at Republican headquarters in Sacramento early Sunday before arriving in Bel Air for an event.
Before a full house at the Stephen S. Wise Temple, Fiorina highlighted the reasons why she's the best candidate to represent the state in Washington D.C.
The former Hewlett-Packard CEO said she knows how to create jobs and called attack ads accusing her of shipping jobs overseas the height of hypocrisy.
Fiorina said Boxer takes campaign contributions from companies that outsource jobs.
"It is Barbara Boxer's policies that drive jobs out of this state and out of this nation," Fiorina said.
California has more registered Democrats than Republicans, but regardless of party affiliation, Boxer encouraged everyone to vote Nov. 2.
"If everybody votes, then we know we are in fact living up to the promise of our Constitution, a government of, by and for the people," Boxer said.