Dr. John MacKieson was born in Scotland on 16 October 1795. He became a licentiate of the Faculty of Physicians and Surgeons at Glasgow in 1815. Dr. MacKieson moved to PEI in 1821 and immediately established a medical practice. In 1833, he was appointed Health Officer for Charlottetown, a position he held until his death.

In 1846, Dr. MacKieson was appointed Superintendent of the Lunatic Asylum and two years later accepted the appointment of Surgeon-General of the Militia. He later became the Medical Attendant of the PEI Medical Society at its inception in [1857?]. He was fired from his position as Medical Superintendent of the Asylum in 1873 and thus assumed private practice in Charlottetown until his death in 1885. Dr. MacKieson married Matilda Brecken on 11 February 1830 and they had a family of six children, two of whom died in infancy.