Von Ziegesar was born in Norwalk, Connecticut. Her childhood dream was to grow up to be a ballerina; she began lessons at age 3 and auditioned for the School of American Ballet at age 8, but was rejected. As a teenager, she commuted to Manhattan at 6 a.m. to attend The Nightingale-Bamford School. After graduating from Nightingale, Von Ziegesar attended Colby College. Then she spent a year in Budapest working for a local radio station. She then returned to the United States to study creative writing at the University of Arizona, only to drop out shortly thereafter.
In New York City, while working at book-packaging firm Alloy Entertainment, she became inspired to create the Gossip Girl series, which present a view of high-end teenage lifestyles. The series climbed to the top of The New York Times Best-Sellers list in 2002. The spin-off, The It Girl, made the list in 2005.
The Constance Billard School for Girls is based upon an exaggerated version of her alma mater, Nightingale. As well, events from the book are based on her extremely wealthy friends who had "those parents" and "those lives", as well as Von Ziegesar's own life as being a gossiper.
Gossip Girl was adapted for television in 2007. The show premiered to mixed reviews and lost more than a million viewers from episode one to two, from 3.65 million to 2.55 million. The rest of the season's viewers went up and down, the highest being 3 million viewers for the season finale and the lowest being 1.80 million viewers for episode eleven.
Controversy and criticism surrounding the show surfaced due to the fact that it failed to show much of the books' plots, character personalities, and other major and minor facts, thus disappointing many fans of the novels. However, von Ziegesar told ABC News that her major plot lines were there and that "at least it takes place in New York".
She resides in Brooklyn with her husband Richard, the Deputy Director of the Public Art Fund, their children, Agnes and Oscar, and their two Cornish Rex cats.