She is of German, French, English, and Choctaw ancestry
Jessica Claire Biel was born in Ely, Minnesota. Her mother, Kimberly (née Conroe), is a homemaker and spiritual healer. Her father, Jonathan Biel, worked for GE and was also an entrepreneur and business consultant. She has a younger brother, Justin, born in 1985. Biel's family moved frequently during her childhood, living in Texas, Connecticut, and Woodstock, Illinois, before finally settling in Boulder, Colorado.
Biel played soccer and also trained as a gymnast.
Biel initially trained to be a vocalist. At age nine, she appeared in several musical productions in her hometown, playing lead roles in productions such as Annie, The Sound of Music, and Beauty and the Beast. Biel auditioned for the a cappella choir the Tufts Amalgamates, but was not accepted.
At twelve, Biel attended The International Modeling and Talent Association conference in Los Angeles where she was discovered and signed by a talent agency. She began modeling for print advertisements, and appeared in commercials for products such as Dulux Paint and Pringles.
Biel also played the character Regrettal, a lead role in a low-budget musical short titled It's a Digital World. At fourteen, after auditioning for several television pilots, Biel was cast as Mary Camden, the second oldest child in the family drama 7th Heaven.