Ben Davis, 26, of Windsor allegedly befriended the victim, a 24-year-old Tiburon man, and his girlfriend while taking a tour of the Lagunitas Brewing Company brewery.
Police said Davis confronted the victim with a knife in a restroom during the tour and demanded his wallet.
Davis allegedly took the wallet, left the brewery and drove away.
Officers responded to the brewery around 5:20 p.m. and learned that the victim's girlfriend had taken a picture of Davis before the alleged robbery.
The photo, along with information the victim learned while talking to Davis, led officers to arrest Davis at his workplace in Windsor, police said.
He was arrested on suspicion of armed robbery and booked into Sonoma County Jail.