Connolly was born in Cork, Co. Cork, Ireland. His father died when he was young and he and his younger sister were raised by their mother. At school, he was a quick study and by age 16 had mastered Greek, Latin and French. He became a novice in the Order of Capuchins. At age 18 he went to Rome to complete his studies for the priesthood. He was ordained as a priest in 1838.
After returning to Ireland for a few years, he eventually travelled to Halifax, Nova Scotia where he became secretary to the prelate. In 1845 he became Vicar-General and administrator of the diocese. In 1851 he was nominated as bishop of St. John, New Brunswick. While in St. John he oversaw the construction of a new cathedral and an orphanage.
In 1859, he was appointed as Archbishop of Halifax. In the first few years of residence he took an interest in the Canadian Confederation movement and actively supported it by writing pamphlets supporting the Union.
After Confederation he took no further interest in political affairs. He died in Halifax due to a 'congestion of the brain' at age 62.
- The Canadian Portrait Gallery, Volume 2. John Charles Dent. 1880.
- "Thomas-Louis Connolly". Dictionary of Canadian Biography (online ed.). University of Toronto Press. 1979–2005.