The legislation, Assembly Bill 1130, was signed on Saturday as part of a broader package of measures aimed at protecting California elections from what the governor's office described as potential interference from President Donald Trump.
California already required influencers to disclose when they were paid to post about state or local races, but the law lacked penalties for non-compliance. Under AB 1130, regulators can fine violators up to $5,000 per instance and refer repeat offenders to law enforcement for possible misdemeanor prosecution.
Democratic Assemblyman Marc Berman, who sponsored the bill, told the New York Times that he introduced it after realising there was "a bit of ambiguity about the [existing] law and how it's enforced."
Texas also requires disclosures for paid political content, and other states are weighing similar regulations. The push for stronger enforcement gained urgency after billionaire Tom Steyer, who ran unsuccessfully for the Democratic gubernatorial nomination earlier this year, paid dozens of influencers to promote his campaign — many of whom initially did not disclose the payments, according to reports.