O'Quigley entered the Civil Service in 1945. In 1950 he was called to the bar and resigned from the Civil Service. He practised law in Dublin and on the Western Circuit. In September 1955 he married Margaret M. Kennedy from Straffan. After the 1957 general election, O'Quigley was elected to the 9th Seanad on the Labour Panel. After the 1961 general election, he failed to be re-elected.
In 1962–65 O'Quigley was junior counsel, initially instructed by Richie Ryan, and later under Seán MacBride, on the legal team of plaintiff Gladys Ryan in Ryan v Attorney General, a water fluoridation controversy case wherein the Supreme Court found the Constitution of Ireland safeguarded the unenumerated right to bodily integrity. After the 1965 general election O'Quigley was elected to the 11th Seanad, this time from the Cultural and Educational Panel. He became leader of the Fine Gael group in the Seanad. He was ill for some time before his death, which took place in Lourdes.
- "John Benignus O'Quigley". Members Database 1919–2005. Oireachtas. Retrieved 17 September 2010.
- "Senator Ben O'Quigley dies in Lourdes". The Irish Times. 30 May 1969. p. 10. Retrieved 17 September 2010.
- Derelict Sites Bill, 1960—Committee Stage. Seanad Éireann debates. 53. 4 January 1961. p. c677.
my home town of Castlebar
- Death of Senator: Expression of Sympathy. Seanad Éireann debates. 66. 9 July 1969. p. c1193.
- "Weddings". The Irish Times. 23 September 1955. pp. 7, 10. Retrieved 17 September 2010.
- The Irish Times, 25 May 1963, p.10
- "Ryan -v- Attorney General". 1 IR. Supreme Court of Ireland. 1965. p. 296. Retrieved 17 September 2010.