Sydney Charles entered the seminary May 1, 1948, and was ordained March 7, 1954.
He first served at St John the Baptist RC, San Juan from May 1954–July 1955, and then was transferred to Santa Rosa, Arima as Assistant Parish Priest until January 1957. He next went to St Philip and St James, Chaguanas as Assistant Parish Priest until March 1960.
Bishop Charles was appointed the parish priest of Our Lady of Mt Carmel RC, Carapichaima until December 1968 but the following year, he was back at Santa Rosa as the parish priest until October 1971. In October of 1971, he was appointed Vicar General of the Archdiocese of Port of Spain and Administrator of the Cathedral of the Immaculate Conception.