Jennifer Love Hewitt was born in Waco, Texas, to Patricia Mae (Shipp), a speech-language pathologist, and Herbert Daniel Hewitt, a medical technician. She has English, Italian, French, Scottish, and German ancestry. She got her first name from her older brother Todd Daniel Hewitt (b. November 8, 1970), who picked the name after a little blonde girl on whom he'd had a crush. Her mother selected Jennifer's middle name, Love (which she goes by offstage), from her best college friend. Her parents separated when she was six months old and her mother raised her in Killeen, Texas.

Hewitt made her official performing debut at age 3 when she sang at a livestock show. At age 5, she was taking tap, jazz, and ballet lessons, which led to her joining the Texas Show Team, who toured the Soviet Union and Europe. When she was 10 her family moved to Los Angeles with encouragement from talent scouts, while Todd stayed behind to finish high school in Texas Jennifer quickly found commercial work and a role on Disney's Kids Incorporated (1984) in 1989. She went through a series of television flops before finally hitting it big on Party of Five (1994) in 1995.