Grodstein was born on November 19, 1975, in New York City. She was raised in a Jewish family by her mother Adele, a Painter, and her father Gerald, a physician. She has a younger sister and a younger brother. She currently lives in Moorestown, New Jersey with her husband Ben, a musician, their son Nate and daughter Penny, and her Bernese Mountain Dog. She wrote a New York Times article on October 31, 2009, entitled "Take Me to the Election" in which she talks about New Jersey's upcoming gubernatorial election and the challenges of discussing it with her class.

In 1997, Grodstein was nominated for the Philolexian Prize, a Columbia University award for literary work. Her novel A Friend of the Family has been selected as a New York Times Bestseller, Washington Post Book of the Year, an Amazon.com Best Book, and a January Magazine Top Ten Book of the Year, as well as a New York Times Editor's Pick. Girls Dinner Club was nominated as a New York Public Library Book for the Teen Age.

In addition to being an author, Grodstein is also a college English professor, beginning her teaching career at Columbia University in New York from 1999 to 2001, and acting as an adjunct professor in the creative writing department in 2004. Grodstein taught creative writing at The University of California in Los Angeles and Cooper Union in New York from 2003 to 2004. In 2005, Grodstein became an assistant professor of English at Rutgers in Camden, New Jersey, where she currently works as an associate English professor and teaches creative writing, modern drama, and fiction and nonfiction courses. She is also a member of the Department of Childhood Studies.

Grodstein's most recent book is about a single mother, Karen, who is writing a memoir for her son, Jake, to read after she passes away. The novel was called "one of the best of 2017" by several critics.