PARIS—A Champs Élysées cosmetics store that attracts six million people a year, nearly as many as the Eiffel Tower, has become the new front line in France's battle over working hours.

French luxury-goods giant LVMH Moët Hennessy Louis Vuitton SA said Monday that it would fight for the right to continue keeping its flagship Sephora perfume and cosmetics store open late at night, after a Paris appeals court ruled that it must close at 9 p.m.

The appeals court said the chain breached work-time regulations by hosting customers until midnight on weekdays and 1 a.m. on weekends at its store on the famous Paris avenue.

Under the ruling, the store will be obliged to begin closing its doors earlier within 10 days, Sephora said.

The question of store hours has long been a contentious subject in France, with retailers, particularly in Paris, saying that flexible hours help them tap into business from tourists.