Tohn was born and raised in Oceanside, Long Island, New York, to physical education teachers Alan and Bella Tohn. She has two older brothers. Tohn began acting professionally at age 10, with an extra role on the PBS children's series Ghostwriter, and was a student at Boardman Middle School when she had her first major role, an appearance on the CBS sitcom The Nanny. After high school, she went to the University of Delaware and majored in elementary education, and in the fall of 1998 was in the a cappella group the Deltones. In November 1999, she starred in the one-act play "This Property is Condemned" by Tennessee Williams at the Chapel Street Theatre.
She has appeared in the films Dawg in 2002 (also known as Bad Boy) alongside Denis Leary, Deuces Wild as Mary Ann, and Return to Sleepaway Camp as Linda. She appeared as Faith in the film Postal and appeared in the 2008 television film Giants of Radio.
She began doing solo acoustic guitar shows in April 2004 and in November 2005 released an EP called The Golden Girl which was recorded at a studio in Tarrytown, New York. She has played at Pianos, The Living Room, CBGB, The Cutting Room, and The Rothko in New York and at Highland Grounds, The Mint, and Wizard Finger in Los Angeles.
In 2007, she appeared in the short films Smile, Discovering The Wheels, The Malibu Myth, The Legend of Donkey-Tail Willie and Catch (where she was shown playing the guitar) which were made during the reality show On the Lot.
In 2009, Tohn appeared on the eighth season of American Idol, and made it through to the Hollywood rounds. She advanced through the Hollywood rounds making the Top 36 for season 8 and was in the first group of 12 to perform going first that night and was eliminated.
In 2011, she appeared on the songwriting-competition reality show Platinum Hit on the American cable network Bravo, as one of 12 aspiring songwriters. She reached 7th place. In 2013, Tohn appeared on House of Lies.
In 2016, she was cast in the Netflix series GLOW.
