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.

Tiegs has been married four times: to advertising executive Stan Dragoti (1970–79), Photographer Peter Beard (1981–83), aspiring actor Anthony Peck (1990–94) who is also a son of actor Gregory Peck, and yoga instructor Rod Stryker (1998–2001). She has three sons: Zackary, with Anthony Peck, and twins Theo and Jaden, who were delivered via surrogacy during her marriage to Rod Stryker.

Tiegs met Photographer Peter Beard in New York in 1978. In 1979, she traveled to Kenya with him on a photographic expedition to investigate the management and widespread destruction of African wildlife; their journey was documented in an Emmy-winning episode of ABC's The American Sportsman titled "Africa: End of the Game." Tiegs and Beard were married in 1981; between 1978 and 1982 she traveled back and forth between the US and Hog Ranch in Kenya. In 1979, LOOK Magazine ran a cover story titled "Cheryl Tiegs: The New African Queen." She was also featured on the cover of Outside in 1980.

In 1980, Tiegs launched a signature line of clothing and accessories for Sears. The first Retail venture by a supermodel, the Cheryl Tiegs collection neared $1 billion in sales by 1989. Tiegs was credited with helping the Retail chain's 1980s turnaround, and once again appeared on the cover of TIME, this time for a cover story titled "Sassy Sears." A doll in her likeness was created in 1990 as part of the "Real Model Collection," which additionally featured Christie Brinkley and Beverly Johnson. In 1995, Tiegs established "Cheryl Tiegs Sportwear," which sold exclusively on QVC. She also developed a line of wigs and hair accessories for Revlon.

Tiegs is active in the philanthropic community, and serves on the Board of Directors of C.O.A.C.H. for Kids and the Earth Conservation Corps. She is a spokesperson for City of Hope and an Ambassador for the International Planned Parenthood Foundation. Tiegs also supports the Macula Vision Research Foundation, I Am Waters, and the Farrah Fawcett Foundation. As an Activist, Tiegs explored the effects of global warming via an expedition to the Arctic. She also participated in a General Motors environmental program, driving a hydrogen powered fuel cell vehicle for three months to raise awareness for zero emissions. In 2010, she appeared on Living with Ed, to promote environmentally conscious living, and was named "Green Star of the Week" by Access Hollywood.

In 2012, Tiegs was a contestant on Celebrity Apprentice, with proceeds from her participation benefiting the Farrah Fawcett Foundation. She has also appeared on NBC's Just Shoot Me, Oxygen's Girls Behaving Badly and in a recurring role portraying herself on Family Guy. Tiegs hosted a 13-part travel adventure series, Pathfinders: Exotic Journeys for the Travel Channel, appeared as a judge on the ABC reality show True Beauty, and was a regular guest on The Oprah Winfrey Show. Additionally, Tiegs has frequently appeared on The Today Show, Access Hollywood, Extra, and The Dr. Oz Show. Her film credits include Vincent Gallo's The Brown Bunny and Walk Hard: The Dewey Cox Story with John C. Reilly. Tiegs created and was featured in Sports Illustrated's exercise video "Aerobic Interval Training."

Tiegs lived in Bel Air, California, but placed her home on the market in May 2015 for $15 million.