On 23 February 1673 Jean-Jacques de Mesmes became the fourth comte d'Avaux at his father's death.

In 1671 Jean-Jacques de Mesmes enlarged his estate at Avaux en Champagne by buying the neighbouring fief of Écry.

He then developed the village of Écry to a small town and renamed it Avaux-la-Ville, while Avaux became Avaux-le-Château.

This new town is today known as Asfeld after Claude Francois Bidal d'Asfeld, who bought the county of Avaux in 1728.

In 1683 Jean-Jacques de Mesmes asked the architect François Romain to build a new church in Avaux-la-Ville.

It is often said that he participated in the signing of the Treaties of Nijmegen but this seems to be due to a confusion with his brother Jean-Antoine, the diplomat.

[citation needed] On 20 September 1671 Jean-Jacques de Mesmes became Provost and Master of Ceremonies of the Ordre des Chevaliers du Saint-Esprit.

[14] His portrait, painted and engraved by Antoine Masson in 1683, shows Jean-Jacques de Mesmes in the robes of a président à mortier with the cross of the Order of the Holy Spirit on its cordon bleu around his neck.

[21] At his death his heirs made a plan how to keep his office as président à mortier in the family.

[22] His son Jean-Antoine was nevertheless promoted to président à mortier without ever having been a maître de recherches.