On the death of his father in 1414, the ten year old Jean inherited the barony of Montmorency and several Lordships, including those of Écouen, Damville and Conflans.

When Jeanne died in September 1431 she was buried at the Cordeliers de Senlis, and she left to her husband Jean her wealthy lands which were enclosed within the territory held by the house of Burgundy.

Jean de Montmorency fought alongside King Louis XI against the self-proclaimed League of the Public Good, led by the Duke of Burgundy, Charles the Bold.

The elder sons were officially disinherited on 24 July 1463, the pronouncement held at the Château de la Chasse, situated in the centre of the forest of Montmorency.

He was mocked in popular songs of the time, and later gave rise to the expression "the more you call him, the more he runs away like Jean de Nivelle's dog".