The incident happened Sept. 2 at about 6:40 p.m. in the bathroom of a restaurant in downtown Hermosa Beach.
Hermosa Beach police said the suspect, David Delgado, asked the victim what his red hat with Russian lettering said.
The suspect then allegedly punched the man several times in the face, stole the hat and ran off.
Police said they used surveillance video to find the suspect and arrest him in his residence in Winnetka.
Delgado is facing charges of robbery and battery with serious injury. He is being held on $100,000 bail.