The 'One You Love' singer and Weisbrodt will tie the knot in Montauk, NY on Thursday (August 23) at the Wainwright family home, reports Page Six.
The couple – who got engaged in November 2010 – are also believed to be hosting a reception at the Shagwong Restaurant. Yoko Ono and Carrie Fisher are both expected to attend.
Wainwright previously revealed that he and Weisbrodt began making wedding plans after New York sanctioned same-sex marriage last year.
"I'm engaged, and me and my partner live in New York and they just passed gay marriage in New York and I was like, 'Goddamn it, now we really have to do this'," he joked at the time.
The singer and Leonard Cohen's daughter Lorca Cohen welcomed a baby daughter in February 2011. Weisbrodt also acts as a father to the child.
Watch Rufus Wainwright and sister Martha Wainwright sing their father Loudon Wainwright III's song 'One Man Guy' below: