During the 1960s, she worked very closely with fashion designer Rudi Gernreich, and developed a signature style that featured heavy makeup and an asymmetrical haircut.

There she was taught by Sydney Pollack and Martha Graham and studied alongside Robert Duvall and Suzanne Pleshette.

[3] While still a student in New York in the 1950s, Moffitt had a short-term contract at Paramount Pictures, and appeared in supporting and sometimes uncredited roles in movies with name stars.

[3] She returned to Los Angeles to begin her acting career in Hollywood,[1] and had parts in Meet Me in Las Vegas with Cyd Charisse; Up Periscope (1956) with James Garner; and Girls Town (1959); with Mamie Van Doren and Mel Tormé.

[9][12] Gernreich first conceived of a topless swimsuit in December 1962, but didn't intend to produce the design commercially.

[13] Gernreich had Moffitt model the suit in person for Diana Vreeland of Vogue, who asked him why he conceived of the design.

Gernreich told her he felt it was time for "freedom-in fashion as well as every other facet of life," but that the swimsuit was just a statement.

When a photo shoot was arranged on Montego Bay in Jamaica,[16] all five models hired for the session refused to wear the design.

[17] To avoid sensationalizing the design, Moffitt, her husband and photographer, William Claxton, and Gernreich decided to publish their own pictures for the fashion press and news media.

[18] Moffitt was initially resistant to the idea of posing topless, and afraid the photograph and ensuing coverage could get out of control.

They wanted a woman to model the monokini, but Moffitt loudly objected because she felt it would exploit Gernreich's intentions.

[28] Moffitt died from complications of dementia at her home in Beverly Hills, California, on August 10, 2024, at the age of 86.

[30] Boyd Rice and Giddle Partridge released a limited edition vinyl recording called Going Steady With Peggy Moffitt in 2008.