According to the US publication, the ceremony took place in a white tent on Boone plantation in Mount Pleasant on Saturday night.
The Gossip Girl star's good friend Florence Welch apparently performed at the wedding with her band Florence and the Machine.
Blake's mum and sister were also spotted in the town, though reps for the actress and her new husband have declined to comment on the reports they are now man and wife.
The notoriously private couple bought a house in New York earlier this year.
This is Blake's first marriage, though she was in a serious relationship with her Gossip Girl co-star Penn Badgely.
Ryan has walked down the aisle before. He was married to Scarlett Johansson, but the pair divorced in 2010 after two years of marriage.