The church's history began in 1832 when Alexander Macdonell established a mission in Priest's Mill[2] (later to be renamed to Alexandria, in honour of Macdonnell [3]) the following year, a church was built and in 1840, the mission was elevated to a parish.[2]
During the pastorate of Fr. Alexander Macdonell the basilica was constructed from 1883 to 1885. In 1890, Pope Leo XIII established the Diocese of Alexandria in Ontario and named Macdonnell as bishop.[2] On October 28, 1890, he was consecrated bishop at St. Finnan. He chose St. Finnan's as his episcopal seat, elevating the church to a cathedral.[4]
The basilica houses a Casavant organ, Opus 284, installed in 1907.[5]