Séan Heuston was born John Joseph Heuston on the 21st of February 1981 in Dublin city. He was the second eldest of four children, born to John and Maria Heuston. Heuston went to a Christian Brothers school where it is said his interest for the Irish language grew. This was also where he was taught a nationalistic view of the history of Ireland. In 1907, he applied for the position of clerk in the Great Southern & Western Railway (GSWR). In order to gain a position as a clerk, Heuston had to undergo a series of examinations where he came 5th out of 136 applicants. From this he was appointed a position within in the GSWR in Limerick. While working in this position, he was known as being a punctual and honest young man.
While living in Limerick, Heuston became involved with the Fianna Éireann movement. This organisation was youth republican movement for boys aged up to 18 years old. Na Fianna helped foster his nationalistic pride for Ireland by training him with drilling and marching and also use of weapons.
During the 1916 Rising, Heuston was in charge of a group of men which seized the Mendicity Institute. Here, Heuston and his men would attack the British troops arriving at Kingsbridge (Heuston) Station.
Heuston was executed by shooting, for his part in the Rising on Sunday the 7th May. His death became controversial because of the fact he was a minor character in the Rising.