The American church group has hit the headlines for its intense protests against the acceptation of homosexuality and has previously picketed the funeral of returning soldiers.
Robin Williams took his own life at his home in the San Francisco last Monday following a battle with depression.
The Church, which is not affiliated with any other group, will target the comedians funeral because he played a gay father in the 1996 film The Birdcage.
Williams had also been a supporter of gay rights.
Westboro tweeted: "Westboro Baptist Church Hopes To Preach In Lawful Proximity To Robin Williams' Funeral – To Warn The Living: Repent Or Likewise Perish."
It's not yet known if the comedian's family will reveal details of the funeral or have a small private service instead.