US Weekly is reporting that the couple married at the same spot where lovers Allie (Rachel McAdams) and Noah (Ryan Gosling) spent their summers in the film. Coincidentally, Lively and Gosling were rumored to be an item in late 2010.
Florence Welch (of "Florence and The Machine") and Bette Midler reportedly performed at the intimate ceremony, which included about 60 guests.
Reynolds, 35, and Lively, 25, met while filming "The Green Lantern" in early 2011. Since they began dating in October that same year, they have kept their romance private.
In April, the two bought a house together in Bedford, New York, for a reported $2 million.
According to TMZ, false rumors that the couple had already tied the knot emerged in July when Reynolds filed a police report against a photographer. In the report, which was published by the site, the officer who took the complaint refers to Lively as Reynolds' "wife."
Reynolds became engaged to Alanis Morissette in 2004, after dating for two years, but the pair split in February of 2007 before exchanging vows.
Reynolds married actress Scarlett Johansson in 2008. They split in late 2010 after just two years of marriage. Back in April, the star confessed to Vogue that the spilt caused her tremendous grief.
Johansson called the spilt "horrible . . . Of course it's horrible. It was devastating. It really throws you. You think that your life is going to be one way, and then, for various reasons or whatever, it doesn't work out."
The 27-year-old added that divorce is "the loneliest thing you'll ever do, in some way."
Following the demise of their marriage, Reynolds was rumored to be linked to his "The Proposal" co-star Sandra Bullock.
In the months before taking up with Reynolds, the actress dated Leonardo Dicaprio. The two were snapped getting cozy in various cities, such as Monte Carlo and Portofino, Italy.
Prior to that, Lively famously dated her "Gossip Girl" co-star Penn Badgley from 2008 to 2010.
On Monday, Badgley voiced his supported for his ex.
"I actually didn't know until last night, but I think it's fantastic," Badgley, told People. "I couldn't be happier for her."