Faced with economic pressures — the war, the general decline of the absinthe trade, and the inherited burdens of a large estate — Jacques-Frédéric sold the family's spirits business in 1950 and leased the entire vineyard to the Nuits-Saint-Georges négociant house Maison Faiveley, departing for a career in banking in Saudi Arabia. The Chambolle vineyards were returned to the family when that lease was renegotiated in 1977, at which point Jacques-Frédéric took direct management, with Bruno Clair engaged as régisseur — though most wine made during this period was still sold in bulk to négociants.
Jacques-Frédéric's son, Frédéric "Frédy" Mugnier (born 1955), had trained as a petroleum engineer and spent his early career on oil projects in Saudi Arabia; he had also worked as a commercial airline pilot for a French airline. Jacques-Frédéric died in 1980, leaving his widow to continue the estate's affairs under Bernard Clair's management while Frédy remained abroad. In 1985, tired of expatriate life, Frédy took a sabbatical and returned to the Château.
He attended the oenology school in Beaune, finished the élevage of the 1984 wines — the first to carry the Mugnier label — and made the 1985 vintage himself, becoming the first member of the family in decades to be present for an entire winemaking cycle. Working initially with just four hectares in Chambolle, Frédy gradually built the estate's reputation through decades of meticulous, low-intervention winemaking.
The transformation accelerated dramatically in 2004, when the 53-year-old farming lease on the Clos de la Maréchale finally expired — on 1 November 2003 — and the vast 9.76-hectare site returned to Mugnier management overnight, more than tripling the estate. Frédy built a new cuverie under the château courtyard to accommodate the expansion, and in 2005 revived the Clos de la Maréchale's white wine, having discovered extraordinary old bottles from the 1940s buried in the cellar. Today Frédy runs the Domaine alongside his wife Jocelyne from the same Château where the family has lived since 1863.