He was born on August 3, 1852 in Pointe Coupée Parish, Louisiana, United States. He was the son of Auguste and Eliska (Labry) Provosty, members of prominent Creole families. His paternal grandfather, also named Auguste, emigrated from Nantes, France, in 1815, and settled in New Orleans; his father served in the Louisiana legislature and was one of the original signers of the secession ordinance adopted by the state at the opening of the Civil War.
He received his early education at home from private tutors, and at Poydras Academy, New Roads, Pointe Coupée Parish. After graduating from the academy he attended Georgetown University, Washington, for a time, but the death of his father compelled him to leave before graduation. Returning to Louisiana, he studied law in the offices of two New Orleans attorneys and attended for a time the law department of the University of Louisiana (now Tulane University).
On January 14, 1873, he was admitted to the Louisiana bar. From 1873 to 1876 he was district attorney for the parishes of Pointe Coupée, Avoyelles, and West Feliciana.
In 1888 Provosty was elected to the state Senate. He was conspicuous in the fight to prevent the recharter of the Louisiana Lottery. He was an active member of the Louisiana constitutional convention of 1898. From 1898 to 1901 he was referee in bankruptcy for the Baton Rouge division of the eastern district of Louisiana, and in 1904 he was appointed chairman of the Torrens Land Law Commission. For a number of years he was legal advisor to the Pointe Coupée police jury.
In April 1901 he was appointed an associate justice of the Louisiana supreme court by Gov. W. W. Heard, and seven years later, in 1908, he was elected to succeed himself. In 1912 he was made a member of the Louisiana Tax Commission.
In January 1922 he was elevated to the office of chief justice of the supreme court of Louisiana, but after holding the position for one year he voluntarily retired from public life. He died in New Orleans upon the seventy-second anniversary of his birth.
As Louisiana senator Olivier Otis Provosty drafted and procured the adoption of the statute creating the Atchafalaya Basin Levee District, said to have been the model for the organic law of the numerous levee districts subsequently created. He also drafted and unsuccessfully advocated the adoption of a bill to put an end to the convict lease system in the state and he was conspicuous in the fight to prevent the recharter of the Louisiana Lottery.
Provosty was studious by nature, and extremely well read in both English and French literature.
In December 1876 he was married to Euphemie Labatut, of Pointe Coupée Parish.
