Tiegs was born in Breckenridge, Minnesota, U.S., to Phyllis and Theodore Tiegs, an auto-assembly lineman turned funeral Director. She and her family moved to Alhambra, California, in 1952. As a senior at Alhambra High School Tiegs posed for a swimsuit ad for bathing suit manufacturer Cole of California; the ad, which appeared in Seventeen, launched her career as a model. Although she enrolled as an English major at California State University, Los Angeles, Tiegs left college before her junior year to pursue her career.