[5] Fontenay began her career with the Miss France Committee in 1954 as its general secretary, often taking on extra roles such as chauffeur, coach and costume designer.

[6] Fontenay became the president of the Miss France Committee in 1981, following the death of Poirot, who had previously held the office.

In 2002, they sold portions of the business to Endemol Shine France, to assist with commercial and television aspects of the organization.

[12][13] In the aftermath of the controversy with Bègue, Fontenay left her position as president of the Miss France Committee, while remaining affiliated with the organization.

She was replaced by Sylvie Tellier, who began to serve as national director of Miss France, taking on much of the responsibilities previously held by Fontenay as the public face of the competition.

In January 2016, Fontenay stepped down from her role with Miss Prestige Nationale in order to retire from the beauty pageant industry.

From 1957 until her death, Fontenay continuously wore a brimmed hat in all of her public appearances, while her outfits were almost always made from a black and white color palette.

According to Fontenay, she had adopted this style at the advice of her long-term partner Louis Poirot, as he claimed that her head was too small for her body, and a hat would disguise that.

[24] She also initially supported the yellow vests protests, despite eventually opposing the movement due to disruptions to traffic.