The 42-year-old actor and his spouse Luciana - who raise four daughters, Alexia, 14, Isabella, six, Gia, four, and two-year-old Stella, together - have set a date for the ceremony, which will take place at the Sugar Beach resort in St. Lucia.
According to the New York Post newspaper, Matt - who married Luciana in a small ceremony in 2005 - has spent $1 million hiring the resort exclusively and guests flying out for the big day include his best friend Ben Affleck and his wife Jennifer Garner, and Hollywood heartthrob George Clooney and his partner Stacy Keibler.
It was recently claimed that the couple had used an alias to hire out the resort.
One staff member said: "The hotel was booked under a different name to Damon.
"We were told that it was a Mr. and Mrs. Naff getting married.
"We then heard that it was Matt Damon and they had been using a false name to stop their secret being found out.
"He was here two months ago to have a look around. A big yacht moored by the beach and he came into the resort."