Basilica of St. John the Baptist, Roman Catholic basilica in St. John's, Canada

The Basilica of St. John the Baptist is a Roman Catholic cathedral near the center of St. John's in the Canadian province of Newfoundland and Labrador. Two towers frame the main entrance, while a copper-clad roof over the nave shapes the skyline of the downtown area.

Construction ran from the excavation of the ground in May 1839 and the laying of the cornerstone in May 1841 to consecration on 9 September 1855, the largest building project in Newfoundland to that date. The cathedral survived the Great Fire of 1892, one of the few buildings in St. John's to do so. Pope Pius XII raised it to minor basilica on 30 May 1955, its centenary; it was designated a National Historic Site in 1983.

The name honours John the Baptist, patron of the archdiocese and of the city. The building was the largest Irish cathedral anywhere outside Ireland when completed, and it remains the mother church of the Roman Catholic Archdiocese of St. John's. Since 2022 the Basilica Heritage Foundation, a non-profit consortium, has owned the building and pledged to protect it while it continues as the city's main Catholic church.

The building sits in a residential area and welcomes visitors daily, though masses and private ceremonies take priority. Guests can walk through the aisles and view the side chapels, but should speak quietly and dress appropriately.

The east tower holds a two-ton bell called the St. John Bell, bought by Bishop Mullock in February 1850. Cast by John Murphy of Dublin, it was the largest bell ever made in Ireland at the time and won a gold medal at the Dublin Exhibition of Irish Manufacturers.