The diocese was established in 1893 and entrusted to the Belgian Jesuits who, the same year, had opened the Pontifical Seminary of Kandy under the direction of Fr Sylvain Grosjean.

The original Diocese of Galle comprised the Southern and Sabaragamuwa civil Provinces of Sri Lanka.

As such it extended from the foothills of Utuwankanda to the coastal parish of Hambantota, covering an area of 403,875 square miles (1,046,000 km2) of the most varied aspect from the point of view of scenery, population and pastoral engagements.

Nearly 90 Religious Sisters extend their supportive hands in serving the people of God in Ruhunu Rata Diocese.

In 1993 Elmo Noel Joseph Perera, a priest originating from the diocese, was installed the Bishop of Galle.