Bernis was a prominent figure in the autobiography of Giacomo Casanova, Histoire de ma vie (Story of My Life), starting from the chapter on "Convent Affairs".

[2] Bernis became known as one of the most expert epigrammatists in the gay society of Louis XV of France's court, and by his verses won the friendship of Madame de Pompadour, the royal mistress, who obtained for him an apartment, furnished at her expense, in the Tuileries, and a yearly pension of 1500 livres.

[4] In 1752, Bernis was appointed to the French embassy at Venice,[4] where he acted, to the satisfaction of both parties, as mediator between the republic and Pope Benedict XIV.

Bernis became secretary for foreign affairs on 27 June 1757,[4] but owing to his attempts to counteract the spendthrift policy of the marquise de Pompadour and her followers, he fell into disgrace and was, in December 1758, banished to Soissons by Louis XV, where he remained in retirement for six years.

But the pressure exercised by the Bourbons of Spain, Naples, and France, and the passive attitude and tacit consent of Austria brought the negotiations to an abrupt termination.

[3] During the French Revolution, he celebrated, in the national church of San Luigi dei Francesi in Rome, a solemn funeral for Louis XVI of France, who had been executed on the guillotine in 1793.

He was reduced almost to penury but the court of Spain, mindful of the support he had given to their ambassador in obtaining the condemnation of the Jesuits, came to his relief with a handsome pension.