Born in 1820 at Sainte-Marie de la Beauce, Quebec, he studied at the Séminaire de Québec (1826-36, 1837-42) and, by all accounts, was a highly regarded student. He obtained a doctorate in Canon law in Rome in 1856 and had a dual career in teaching and the episcopacy.
He was a teacher, director, prefect of studies and superior at the Séminaire de Québec; he helped found Université Laval in 1852 and served as its second rector (1860-66, 1869-71).
At the urging of the Canadian government and many, in 1886 Pope Leo XIII made Taschereau a cardinal. He was not able to stay in post for long as illness forced him to turn over his workload to Louis-Nazaire Bégin. He died in Quebec City on April 12, 1898.