Szohr is of Hungarian and one quarter African-American descent. She was born in Menomonee Falls, Wisconsin, a place she describes as a "family-oriented small town". The oldest of five children, Szohr played soccer, served on the student council, and was part of the cheerleading squad while in school. She started a cleaning company with a friend, cleaning their teachers’ houses.
Szohr started modeling at age six. Her first national campaign was for Quaker Oats at age ten, and she also appeared in print ads for Kohl's department store. Subsequent modelling gigs followed, including prints for Crate & Barrel, Mountain Dew, Sears, Jockey and JanSport. Szohr graduated from Menomonee Falls High School a semester early and moved to Los Angeles with her mother at the age of 17 to pursue an acting career. She told Seventeen magazine that she "almost moved home like five times.
Szohr earned her laurels as a frequent presence on U.S. television during the 2000s. She appeared in numerous guest stints in television series such as That's So Raven, My Wife and Kids, What I Like About You and Joan of Arcadia. She also appeared in three episodes of CSI: Miami as Samantha Barrish.
In 2007, she appeared in a major recurring role as Laura for six episodes in the now cancelled ABC Dramedy television series What About Brian. Along with Stacy Keibler, she played a neighbour to the main character Brian O'Hara (Barry Watson). She also appeared in the music videos for Best Days by Matt White and Over You by Daughtry, in which she played Sarah.
In the same year, Szohr earned her breakthrough role on the hit CW Teen Drama television series Gossip Girl. Based on the novel series written by Cecily von Ziegesar, Gossip Girl’s premise follows the lives of privileged young adults on Manhattan's Upper East Side in New York City. She plays Vanessa Abrams, Dan Humphrey’s (Penn Badgley) childhood friend and occasional love interest. Szohr described her character to Ocean Drive magazine, "Vanessa doesn't change for other people. She says what she thinks. [...] she’s just a badass girl from Brooklyn". The portrayal of Vanessa in the TV series has drawn criticism from Ziegesar, who claimed Vanessa is "one character they ruined Originally cast as a recurring role she became an additional series regular after the season one episode The Blair Bitch Project.
She has appeared in small roles in films such as Somebody Help Me, The Reading Room and Fired Up.
Szohr next signed on to Dimension Films' horror Piranha 3D directed by Alexandre Aja. The film was a remake of the 1978 comedy-horror Piranha. In the film, she played Kelly Driscoll, "a hot young townie caught up in the excitement of co-eds who have descended upon the area for spring break. The role required her to be underwater; Szohr later told the New York Daily News that filming was difficult because she was "not the best swimmer. Filming began in June 2009, and the film was pushed back from its original release date in March to August 2010. She also appeared in a Funny or Die video promoting the film alongside Kelly Brook and others.
She was awarded the Breakthrough Actress in Film award at the 2010 Breakthrough Of The Year awards for her work in Piranha 3D.
In April 2010, Szohr joined the cast of the romantic comedy Love, Wedding, Marriage, along with Mandy Moore and Kellan Lutz. The film began principal photography in April 2010 and was filmed in New Orleans.
Szohr will have a role in the independent post-apocalyptic sci-fi movie, Hirokin which began production in July 2010. Her role as Orange has been described as a "cunning temptress". She is also set to star in the Eric Amadio directed indie film, Walks alongside Brittany Snow and Rumer Willis.
She will star in the indie drama Art Machine as an outlaw hipster and a pyrotechnic artist. Directed by Doug Karr, the movie is being shot in New York.
In May 2011, it was confirmed that Jessica would not be appearing as a regular cast member on the upcoming 5th season of Gossip Girl, and that her character Vanessa would be cut along with Taylor Momsen's. However, their characters may appear as guest stars in future episodes.
Szohr had been in a relationship with her Gossip Girl co-star, Ed Westwick from late 2008. In an interview with Teen Vogue, Szohr admitted the two were "just friends" for a year but decided to give a relationship a go when they found themselves single. "It can be a little awkward […] It kind of just happened." Szohr said in the interview, "when all of a sudden [you have feelings for] someone you'd call to talk about a different boyfriend.In March 2010, Westwick split from Szohr but the two reunited whilst filming season 4 of Gossip Girl.
Szohr has an affinity for snowboarding, hiking, yoga and soccer. She describes her hobbies as a result of her being "from Wisconsin". Szohr has also said that she is a huge Green Bay Packers fan. She also told Parade magazine that, in order to avoid real-life gossip, she doesn’t "read blogs, I don't have MySpace, I don't have Facebook or Twitter -- none of that."She currently resides in New York.
Szohr’s real-life fashion is what she calls "simple and casual." Speaking to Vogue, she said "I wouldn’t say I’m trendy or follow any particular trends." She also has several tattoos, including her grandparent’s anniversary on her left arm and a cherub on her foot.
In 2010, Szohr was named in People magazine's "100 Most Beautiful People in the World".