Jean de Mailly, Bishop of Noyon, was one of the principal members of the English King's Council, and a very fanatical Burgundian.

He was a licentiate in law, councilor of Parlement (1401) master of petitions of the hôtel (1418), and president of the Chamber of Accounts in 1424. He became dean of Saint Germain l'Auxerrois at Paris and was called to Noyon as Bishop by Martin V on July 20, 1425.

The following year, with Louis de Luxembourg, he was designated to pacify the dispute concerning heretic witchcraft between the Bishop of Paris and Jean Graverent, Inquisitor. From 1424 on we find him at Rouen present at the sessions of the Exchequer, and he was appointed by the English government.

He accompanied the young King to Paris, as well as Pierre Cauchon, and was present at Nôtre Dame as ecclesiastical peer, at Henry VI's coronation ceremonies. He subscribed to the safeguard accorded to Jeanne's judges.

Jean de Mailly was not very old at the time of the Rehabilitation (he was born about 1396). He alleged, however, that he had been present at only one session of the Trial and declared that he remembered nothing about it. He was, nevertheless, present at the abjuration scene and at the burning of the Maid.

In 1443 Jean de Mailly received in procession Charles VII in his city of Noyon. In 1435 he had taken part in the embassy which announced to Charles the happy conclusion of the Peace of Arras.

He died February 14, 1472, leaving to his church his Bible, a manuscript on vellum.
He was above all else a diplomat and financier.