The Diocese of Châlons is a Latin Church ecclesiastical territory or diocese of the Catholic Church in Châlons-sur-Marne, France. The diocese comprises the department of Marne, excluding the arrondissement of Reims.

Châlons-en-Champagne is a city in the Grand Est region of France. It is the capital of the department of Marne, despite being only a quarter the size of the city of Reims.