Pierre was the son of Gilbert Simonet, an alumnus of the École Polytechnique and an engineer of bridges and roads in French Indochina.

He enlisted in de Gaulle's Free French Forces on 1 July 1940 where he set out to be an aviator, but was denied due to his lack of a pilot's license.

Simonet left the United Kingdom on 29 August 1940 for an expeditionary force in Dakar which sought to rally French West Africa in favor of Free France.

He took part in the Syria–Lebanon campaign in June and July 1941, the result of which was decided in Damascus as a victory for Free France.

Simonet served in the 1st Free French Brigade under General Marie-Pierre Kœnig and participated in the North African campaign from January to July 1942.

Simonet's brigade was engaged in the Second Battle of El Alamein in October 1942, aiding the Eighth Army in the Tunisian campaign against the Afrika Korps, led by Erwin Rommel.

On 18 June 1945, following the Liberation of Paris and Victory in Europe Day, he piloted one of the three Piper Cubs which passed under the Eiffel Tower.

He began taking courses at the Institut national de la statistique et des études économiques and the University of Paris.

[2] During the commemorations of the 80th anniversary of the Appeal of 18 June, British Prime Minister Boris Johnson announced that the last four Companions of the Liberation, Edgard Tupët-Thomé, Hubert Germain, Daniel Cordier, and Pierre Simonet, would become Honorary Members of the Order of the British Empire.

[4][5] President Emmanuel Macron stated in a press release that "he was indeed a hero: no matter how much he refused this title, he had all the attributes - courage, moral strength, a sense of duty".

[6][7] Minister of the Armed Forces Florence Parly and her Secretary of State, Geneviève Darrieussecq, issued a joint statement, saying "the whole country will remember his courage, his tenacity and his modesty".