She served as the first lady of the United Nations during the two terms her husband Javier Pérez de Cuéllar was Secretary-General (1982–1991) and later as his hostess during his tenure as Prime Minister of Peru (2000–2001) and Peruvian ambassador to France (2001–2004).

Following earlier marriages, she married Javier Pérez de Cuéllar and served as his advisor and hostess during diplomatic missions and his tenure at the United Nations.

[13] Javier was a Peruvian lawyer and diplomat, having served in France, Britain, Bolivia, Brazil, Switzerland, the Soviet Union, Poland, and Venezuela.

[13] Although not an official post,[6] as first lady,[15] Pérez de Cuéllar had numerous responsibilities as the hostess of world leaders and dignitaries and as an advisor and confidant to her husband.

[6] A humanitarian mission to Ethiopia during the 1984 famine had a profound effect on her awareness of suffering and the disconnect between the amount of money governments spend to eliminate global poverty and that spent on war and armaments.

[20] The organization was established to address problems, such as lack of education, food, health care, shelter, and adequate clothing for mothers and children in Southern Africa, which mainly stemmed from on-going conflicts.

[22] In addition to her obligations hosting the representatives of heads of state and government and accompanying Javier to more than 20 countries, Pérez de Cuéllar was responsible for caring for the visiting wives of diplomats.

[23] A particularly important luncheon involved hosting Raisa Gorbacheva, when her husband Soviet leader Mikhail Gorbachev spoke the to United Nations in 1988.

[25] Other women in attendance included socialite and philanthropist Brooke Astor, cosmetics icon Estée Lauder, and television personality Barbara Walters.

[29] Along with other heads of state, and women such as Benazir Bhutto, Barbara Bush, and Princess Françoise Lobkowicz, Pérez de Cuéllar received the Together for Peace award at a celebration held at the UN in 1989.

[31] Pérez de Cuéllar represented and spoke on behalf of the United Nations at the dedication of the Strawberry Fields Memorial to John Lennon in New York City's Central Park in 1985.

[33] She spoke again on behalf of the United Nations and greeted Lennon's spouse Yoko Ono in the 1990 ceremony, when Imagine was broadcast as a peace tribute world-wide in honor of what would have been the singer's 50th birthday.

[35][36] Organizing a trip for the European WMF president Bertrand du Vignaud and other supporters in 2001, she proposed that they visit colonial churches from the Inca era between Cuzco and the archaeological site at Pikillaqta.

[39][40][41] She was remembered at the time for her service to the United Nations as an elegant and gracious hostess, and advisor to her husband, in addition to her global efforts on cultural and historic preservation.