Some of the past pupils of Knockbeg college have recorded some notable achievements;

James Fintan Lalor was a leader of the Young Irelanders, as well as a well-known writer.

Rev. Dr. Matthew Cullen, former Bishop of the Kildare and Leighlin diocese, position held from 1927-1936,

Frank O’Meara, (1853-1888) , Well known artist, his work included; ‘Old Woman Burning Leaves’ and ‘Reverie and Old Mill at Grez’.

Kevin O’Higgins was a Nationalist and a Pro- Treaty TD from the Laois/Offaly constituency. O’Higgins was also a member of the first Dáil and was elected as Minister for Home Affairs and Vice President of the Executive Council in the Dáil. Kevin O’Higgins was also the Founder of the Garda Síochána. O’Higgins was assassinated by the Irish Republican Army in 1927.

Tommy Murphy ,  Ex-Laois Gaelic Footballer, who was named in the centre of the field in the Gaelic Athletic Association’s Team of the Millennium.

Paddy Lalor, Former Minister for Industry and Commerce and Fianna Fáil TD,

Rev. Dr. Laurence Ryan, Former bishop of Kildare and Loughlin, who was in office from 1987-2002.

Charlie Flanagan, is a Fine Gael TD representing Laois Offaly. He was the Minister for Justice and Equality until 27 June 2020. He was appointed to the role on 14 June 2017, having previously served as Minister for Foreign Affairs and Trade. He was Minister for Children and Youth Affairs for a period in 2014.

Liam O’Neill held the  position of Chairman of the Leinster Council and President of the GAA.

Colm Begley was a former Professional Aussie Rules player with the Brisbane Lions and St. Kilda Saints.

Thomas Daly is currently under contract with Leinster Rugby and has captained the Irish rugby sevens team.