Mariska Magdolna Hargitay was born in Los Angeles, California, to actress Jayne Mansfield and bodybuilder and actor Mickey Hargitay. She is the youngest of their three children.

Mariska experienced a traumatic event at the age of three when her mother, Jayne Mansfield, died in a car accident. Mariska and her two brothers, Miklós and Zoltán, were in the car but survived. She bears a scar on her head from the accident.

Following her mother's death, Mariska and her brothers were raised by their father, Mickey Hargitay, and their stepmother, Ellen Siano. Ellen played a significant role in their upbringing and provided a stable home environment.

Growing up in a family with strong ties to the entertainment industry, Mariska developed an early interest in acting. She participated in school plays and showed a natural talent for performing.