California is one of five states competing for a $5 billion Tesla battery plant.
Brown announced signing AB2389 by Democratic Assemblyman Steve Fox of Palmdale on Thursday.
A legislative debate that lasted for hours focused nearly entirely on the 15-year tax incentive for Lockheed Martin, which is bidding for a $55 billion federal aerospace contract. Competitor Northrup Grumman complained it was unfair.
The tax changes, including language helping battery manufacturers, were sought by the governor.
Fox's office referred questions about the Tesla tax credit to Brown's GO-Biz Department, which issued a statement saying it was dedicated to promoting manufacturing in California.