The jury of 10 women and two men had deliberated about 13 hours since Friday before it returned the verdict to a packed courtroom shortly before noon.
Afterward, Judge Nina N. Wright Padilla took the unusual step of coming down from the bench and asking all 12 to approach so she could shake their hands.
"I hope you continue your work in a law-abiding way," said Padilla.
The 12 - one woman and 11 men - were arrested trying to call attention to what they called Wells Fargo's "racist predatory lending" policies that caused a disproportionately large number of home foreclosures in African American neighborhoods.
Last July, Wells Fargo, the nation's largest mortgage lender, agreed to pay $175 million to settle allegations by the U.S. Justice Department that independent brokers originating its loans charged higher fees and rates to minority borrowers than they did to white borrowers with similar credit risks.
The verdict left the Occupy protesters with a sense of vindication.
"If this jury has found us innocent, then it must mean that Wells Fargo is guilty," said 71-year-old Willard R. Johnson, one of the 12 on trial.
"We have proof of the importance of free speech in a democracy, especially taking on corporate power," said defense attorney Paul Hetznecker, one of seven lawyers who represented the protesters without charge. "It's about speaking truth to power and it's part of a long-standing tradition in this country."
The arrests of the 12 occurred during a season of Occupy encampments and protests in Center City, but the Wells Fargo sit-in - a confrontation between free speech and private property rights - was the first where Occupy protesters were convicted of a crime.
Last June, Municipal Court President Judge Marsha H. Neifield found all guilty of the trespass charge and fined each $500 plus court costs.
Under Philadelphia court rules, people found guilty in Municipal Court have the right to a new trial in Common Pleas Court.
The current trial began Feb. 25 with the defense arguing that the sit-in was protected by the First Amendment. They also contended that the protest served a greater good for society that trumped the trespass charge.
Assistant District Attorney Jim Stinsman argued that the Occupy protesters' First Amendment rights did not apply once they went inside the branch because they were then on private property.
Contact Joseph A. Slobodzian at 215-854-2985, firstname.lastname@example.org, or @joeslobo on Twitter.