Dr. Everard died in 1821 and left £10,000 "for the purpose of founding a college to provide a liberal education of Catholic youth destined for the priesthood and professional/business careers".

[3] The college was built on church land bought from a local Protestant minister,[2] the first stone was laid by Dr. Robert Laffan Archbishop of Cashel, on 6 July 1829, in the presence of Daniel O'Connell.

[citation needed] In 1842, a philosophy department was added to the college, and with some students becoming candidates for the priesthood for the first time.

[citation needed] In 1842, Archbishop of Cashel Michael Slattery established a foreign mission department in St. Patrick's College, Thurles, many of its graduates going to the United States, Australia and New Zealand.

[citation needed] In 1849, the University of London[5] allowed Thurles to offer degrees in arts and laws,[6] following an example from St. Patrick's College, Carlow.

[2] In 1965 a new wing was opened by Archbishop of Cashes, and former Thurles professor Rev Dr. Morris, the new building included College Oratory, students’ rooms and an assembly hall.

[12] In 1988, after a gap of 81 years, lay students were readmitted, and the college had its courses validated by the National Council for Educational Awards (NCEA), such as the BA in theology which allowed graduates to teach in secondary schools,[13] and since 2001 when the NCEA was replaced by the Higher Education and Training Awards Council (HETAC) has validated the colleges degree courses.

The St. Patrick's Campus has a full-scale Gaelic Athletic Association (GAA) pitch onsite and also tennis and basketball courts, and a handball alley.

[16] Others associated with Irish parishes include Archbishop of Cashel & Emly Dr. Thomas Morris DD, who taught at the college from 1942 until 1960, Bishops Dr. Michael Russell former professor of moral theology and sacred eloquence (1948–1965) as well as vice-president (1962–1965), and former college president Dr. William Lee of Waterford.

Bishop Thomas F. Quinlan of Borrisoleigh spent over four years in the college before joining the Columban Missionary Society.

Canon John Hayes the founder of Muintir na Tíre studied in Thurles for a time.

John Finucane, Home Rule MP for East County Limerick from 1885 to 1900 studied at the college, taking first honours in rhetoric, logic and metaphysic.

), professor of church history from (1878–1903), vice-president (188?–1903) and president (1903–1914), Ryan was responsible for the pallotines coming to Thurles (leaving them his house), reestablishment of the Irish College in Louvain and he also bought Glenstal Abbey for the benedictines,[19][20] Canon Garret Cotter, Rev.

[22] Starting in 1970 every five years the college hosts an international reunion of former students from Ireland and abroad who studied for the priesthood in Thurles.

In 2012, the college celebrated its 175th anniversary, and were honoured by a civic reception by Thurles Town Council held in the Source Library.

[10] In September 2016 a new deal was agreed which will see the 3rd level institution work with Mary Immaculate College in becoming a linked provider to the Limerick Centre of Excellence.