Born in Vĩnh Hội, Saigon, he was sent to the Issy-les-Moulineaux Seminary in France to complete his studies and was ordained a priest in June 1953 at Notre-Dame de Paris cathedral.
On 1 July 1974, the Holy See appointed him Auxiliary Bishop of Saigon (present-day Ho Chi Minh City).
On 11 August 1974, at the Notre-Dame Saigon, he was ordained Titular Bishop of Selsea by Cardinal Agnelo Rossi, Prefect of the Congregation for the Evangelization of Peoples.
In 1993, he was named Apostolic Administrator of the Archdiocese of Ho Chi Minh City, due to poor health condition and then death of Archbishop Paul Nguyễn Văn Bình, until the installation of Archbishop Jean-Baptiste Phạm Minh Mẫn in 1998.
On 1 April 2005, Bishop Nicolas resigned due to age limit, and was succeeded by Paul Nguyễn Thanh Hoan.