The Diocese of Thalassery was erected on 31st December 1953 for the Catholics who migrated from the erstwhile states of Travancore and Cochin. The boundaries of the Diocese were the whole of former Malabar district up to the Bharathapuzha, parts of Palakkad District and erstwhile Valluvanad Taluk. The Diocese was bifurcated in 1973 for the erection of the Diocese of Manathavadi; in 1974 to form the Diocese of Palakkad; and in 1986 to constitute the Diocese of Thamarassery. At present, the jurisdiction of the Diocese spreads over the revenue districts of Kasaragode and Kannur in Kerala State and South Kanara and Coorg in Karnataka State. The headquarters of the Diocese is at Thalassery, Kannur District. The patron of the Diocese is St. Joseph.
