He was born in Paris, in the Loménie family from Flavignac, some twenty kilometres from the city of Limoges, in the Limousin region of France, currently part of Nouvelle-Aquitaine.

They continued in high ranking positions in the state, occupying important government posts in foreign affairs under Louis XIV and towards the end of the Ancien régime at the ministry of war.

[9] Once in power, he succeeded in making the parlement register edicts dealing with internal free trade, the establishment of provincial assemblies and the redemption of the corvée.

The struggle of the parlement against Loménie de Brienne ended on 8 May in its consenting to an edict for its own abolition, with the proviso that the Estates General should be summoned to remedy the disorders of the state.

[12] Loménie de Brienne, who had in the meantime been made Archbishop of Sens (confirmed by Rome on 10 March 1788), now faced almost universal political opposition.

He was to follow his uncle in swearing the oath to the Civil Constitution of the Clergy, but along with other members of the family the coadjutor was guillotined on 10 May 1794, having in the meantime repented of his submission.

[14] After the outbreak of the French Revolution Étienne-Charles returned to France, and took the oath of the Civil Constitution of the Clergy in 1790, one of the few bishops of the Ancien regime to do so,[15] and he encouraged many of his priests to do the same.

Though he had refused to ordain constitutional bishops,[17] at the height of the Revolution, on 15 November 1793, he renounced the priesthood, but his past and present conduct made him an object of suspicion to the then prominent revolutionaries.

He was arrested at Sens on 18 February 1794, and that same night died in prison, whether from a stroke or by poison, some said by suicide, though the shock of the failure of his bravado and all his frantic efforts at survival would perhaps have been enough to kill him.