The "Girls" star and Van Veen, who co-founded College Humor, exchanged vows in front of celebrity guests including Lena Dunham, Katy Perry, John Mayer and Seth Meyers, People reported.
The gorgeous bride walked down the aisle in an Oscar de la Renta gown. Williams shared a photo from the wedding on her Instagram account early Sunday morning.
The 27-year-old, who is the daughter of journalist Brian Williams, told Glamour magazine in March 2014 that she would like to have children some day. "My goal is to create a career I can walk away from and become a mom," she said.
Congratulations to the happy couple!