Manuel Castro, 30, was arrested Wednesday, the Los Angeles Times reported. The sprayed slogan was discovered early on the morning of Aug. 3 at a Chick-fil-A in Torrance.
The restaurant chain became controversial when its president, Dan Cathy, gave an interview opposing same-sex marriage. The privately held chain has long reflected the beliefs of its founding family by closing on Sunday.
Aug. 3 also happened to be "National Same-Sex Kiss Day," when many gay couples came to Chick-fil-A to smooch.
Sgt. Steve Jenkinson of the Torrance police said evidence found at the scene led investigators to Castro. But he made it easy for police by giving interviews admitting the vandalism.
The day before his arrest, Castro told The Huffington Post he believed he had contributed to a discussion of "tolerance and acceptance."