Mercier was born in Lowell on November 8, 1933, to the late Peter and Lillian (Rodrigue) Mercier. He was a student of St. Joseph High School, and a lifelong resident of Lowell. He was a long-time member of the former Ste. Jeanne d'Arc Church in the Pawtucketville Section, and also founded Mercier Realty in 1985.
