He was born in Paris, where he was the last maître of the Chapelle royale before the French Revolution.
He also became the leader of the music academy of Orléans (1757-1765), which became a big yet temporary success soon after his appointment.
[3] Two of his works won both 1st and 2nd place in a contest for composers of the Concert Spirituel, organised by the Tuileries in Paris, 1768.
The majority of his other compositions have been saved by his widow Marie-Françoise de Beaumont d'Avantois, who was a singer at the same court.
[3][2] A previously unknown notebook by Giroust titled Regles de composition was recovered in 2015.