The Diocese of Belley-Ars is a Roman Catholic diocese located in eastern France. It was established in 1822 and is part of the ecclesiastical province of Lyon. The diocese covers the departments of Ain and Savoie, with its seat in the town of Belley. The diocese is known for its association with Saint John Vianney, the patron saint of priests, who served in the village of Ars. The diocese emphasizes pastoral care and community engagement, reflecting its commitment to the spiritual needs of its parishioners.