The 25-year-old Girls star is set to wed her boyfriend of three years, Ricky Van Veen, her rep confirms to PEOPLE exclusively.
The daughter of NBC news anchor Brian Williams met the College Humor co-founder, 33, through mutual friends and told Glamour earlier this month that she would "walk away from" her career in order to have kids.
"I'd love to be a mom – and not have to bring my kids into my trailer … Or a balance [of both]," said Williams, who plays Marnie on the hit HBO show. "But you've [got to] call it on the fly to a certain extent."
In an interview with Larry King in January, Williams admitted that her boyfriend and friends were getting used to her newfound fame, and were "very good at taking cell phone pictures" with fans.
And when asked by King what her dad thought of Van Veen, Williams smiled as she replied, "He likes him a lot."