Born François-Louis Croisnu, he was the son of Louis Croisnu, who adopted the name Crosnier,[1] and Marie-Barbe Constantin, concierges of the Opera, who kept the post for over 35 years.

However, failing to achieve great success and acquiring a large fortune through marriage, he abandoned playwriting for other endeavours.

He was very successful managing the Opéra-Comique, a theatre in full-blown financial crisis when he took over in 1834.

He brought the theatre back to prosperity by staging a large number of successful works, among the most remarkable being Lestocq and Le cheval de bronze by Daniel Auber, L'éclair by Fromental Halévy, Les chaperons blancs by Auber, Sarah by Albert Grisar, the Le postillon de Lonjumeau by Adolphe Adam, L'ambassadrice and Le domino noir by Auber, Le brasseur de Preston by Adam, La fille du régiment by Gaetano Donizetti, and Zanetta, Les diamants de la couronne, Le duc d'Olonne, and La sirène by Auber.

[1] He died at Lisle, in the château de l'Épau, near Vendôme, the town where he was mayor, on 1 September 1867 (acte n° 4, vue 442/469 du registre) and is buried in the Montmartre Cemetery in a chapel of the 15th division, where he lies alongside his father and his two spouses.