Cusack is born on the eastern fringe of the Burren to Irish speaking parents in Carran, County Clare on September 20, 1847, during the Great Famine. He becomes a national school teacher and in 1874, after teaching in various parts of Ireland, becomes a professor at Blackrock College, then known as the French College. In 1877, he establishes his own civil service academy, Cusack’s Academy, in Dublin which proves successful in preparing pupils for the civil service examinations.
A romantic nationalist, Cusack is also reputed to have been associated with the Fenian movement. He is active in the Gaelic revival, initially as a member of the Society for the Preservation of the Irish Language which is founded in 1876, and later the Gaelic League who in 1879 breaks away from the Society. Also in 1879, he meets Pat Nally, who is a member of the Irish Republican Brotherhood and a leading nationalist and athlete. He finds that he and Nally agree on the influence of British landlordism on Irish athletics.
He would recall how both Nally and himself, While walking through Phoenix Park in Dublin and seeing only a handful of people playing sports in the park so depresses Cusack and Nally that they agree it is time to “make an effort to preserve the physical strength of [their] race.” Nally organises a National Athletics Sports meeting in County Mayo in September 1879 which is a success, with Cusack organising a similar event which is open to artisans in Dublin the following April.
On November 1, 1884, Cusack together with Maurice Davin, of Carrick-on-Suir, County Tipperary, calls a meeting in Hayes’ Commercial Hotel, Thurles, County Tipperary, and founds the Gaelic Athletic Association (GAA). Davin is elected president and Cusack becomes its first secretary. Later, Archbishop Thomas William Croke, Archbishop of Cashel & Emly, Michael Davitt and Charles Stewart Parnell become patrons. Cusack also becomes involved in the Irish language movement, founding The Celtic Times, a weekly newspaper which focuses on “native games” and Irish culture.
Michael Cusack dies in Dublin on November 27, 1906 at the age of 59. He is buried in Dublin’s Glasnevin Cemetery.