The snaps show the comedy superstar mingling with other partygoers at a reception hosted by local artist Mark Jaeger at a venue in San Francisco.
Williams was pictured at the event on Saturday night, just 36 hours before his body was found at his home in nearby Marin County. The star is believed to have hanged himself after suffering a long bout of depression.
Jaeger tells TMZ.com that Williams seemed in good spirits at the bash and was spotted laughing with other guests, while he also claims to have held a discussion with the actor about a potential movie script.
Williams attended the party with his wife Susan Schneider, who is also seen in the snaps.