The Roman Catholic Diocese of Belgaum (Latin: Belgaumen(sis)) is a diocese located in the city of Belgaum in the ecclesiastical province of Bangalore in India.

The Belgaum Diocese was erected on 19 September 1953 by the papal bull Summa illa Sollicitudo of Pope Pius XII.

Two civil districts of Belgaum and North Kanara were separated from the Archdiocese of Goa and two other civil districts of Dharwad and Bijapur were taken from the Diocese of Pune in forming the Diocese of Belgaum.

By the papal bull Christi Missium of Paul VI, the North Kanara District was separated from the Belgaum Diocese to form the Karwar Diocese on 24 January 1976.

It now consists of the civil districts of Belgaum, Bijapur, Bagalkot, Dharwad, Gadag and Haveri in Karnataka State and the Chandgad taluka in Kolhapur District of Maharashtra State.