Julia Hummer's childhood was marked by her parents' separation, which led her to spend time with both her mother and in a youth home. She attended high school in Itzehoe and later dropped out to move to Hamburg.
Her chance encounter with director Sebastian Schipper, who discovered her after seeing her portrait on the cover of "jetzt" magazine in 1998, led to her first film appearance in his comedy "Absolute Giganten" (1999). She also appeared in the TV crime film "Stahlnetz: The Witness" the same year, and in the comedy "Tolle Lage" and the film "Crazy" (2000) the following year. Her role in "Tatort - The Little Witness" (2000) earned her the Günter Strack Television Prize the following year.
In 2000, Hummer starred in the film "Internal Security" as the terrorist's daughter "Jeanne", earning a nomination for the German Film Prize as Best Young Actress. She continued to appear in films such as "Tatort - Dead sind du!", "Heidi", and "Honolulu" in 2001, and "Because I'm good!" and "99 Euro Films" in 2002. Her role in the tragic comedy "Eierdiebe" in 2003 marked her first appearance as a singer, and she went on to release her first album in 2005.
In addition to her music career, Hummer continued to work in film, appearing in "Northern Star" in 2003 and "Ghosts" in 2005, the latter of which premiered at the 55th Berlinale in February 2005.
