Diarmuid O'Flynn is the founder of the Ballyhea Says No campaign, and in 2014 began working as one of MEP Luke Ming Flanagan's parliamentary assistants. He was the Irish Examiner's chief hurling correspondent until his relocation to Brussels in 2014. As founder of the Ballyhea Says No protest movement, which has been marching against payments to bondholders since 2011 and has been described by journalist Michael Clifford as "the conscience of a nation", O'Flynn has repeatedly called for debt justice for Ireland. Among those to have endorsed his position are the literary editor Fintan O'Toole and economists Constantin Gurdgiev and Stephen Kinsella.
In June 2011, he embarked on a three-day run then participated in a short march in Dublin before hand-delivering a petition to the Fine Gael-Labour coalition government. In August that year, he went on a seven-day “bread and water” fast, losing about a stone in weight.
He ran as a candidate in the South constituency at the 2014 European Parliament election, where he was considered a "dark horse" challenger, received the support of Ireland's top business website Finfacts and was eliminated on the 10th count. In November 2014, he was appointed parliamentary assistant to Midlands–North-West MEP Luke 'Ming' Flanagan.
- Ryan, Órla (3 March 2014). "Diarmuid O'Flynn is calling for a debt write down for Ireland and the abolition of the euro". TheJournal.ie. Archived from the original on 18 March 2015. Retrieved 3 March 2014.
- Clifford, Michael (12 May 2014). "Diarmuid O'Flynn is the hurler on the pitch for protest votes". Irish Examiner. Archived from the original on 18 March 2015. Retrieved 12 May 2014.
- Reilly, Gavan (27 March 2013). "Ballyhea protestors in Brussels to meet MEPs from economics committee". TheJournal.ie. Archived from the original on 18 March 2015. Retrieved 27 March 2013.
- Freyne, Patrick (19 May 2014). "Underdog candidates at a disavantage faced with the might of party machines". The Irish Times. Archived from the original on 18 March 2015. Retrieved 19 May 2014.
- Kelly, Niall (3 June 2011). "O'Flynn bitterly disappointed by response to anti-bondholder protest". TheJournal.ie. Archived from the original on 18 March 2015. Retrieved 3 June 2011.
- Kelly, Niall (3 August 2011). "Irish Examiner sports journalist renews his anti-bondholder protest by launching a seven-day "bread and water" fast". TheJournal.ie. Archived from the original on 18 March 2015. Retrieved 3 August 2011.
- Hennigan, Michael (8 May 2014). "European Parliament: Vote No. 1 for Diarmuid O'Flynn in Ireland South". Finfacts. Archived from the original on 18 March 2015. Retrieved 8 May 2014.
- Riegel, Ralph (27 May 2014). "Independent Diarmuid O'Flynn eliminated from Ireland South race after count 10". Irish Independent. Retrieved 27 May 2014.
- Gubbins, Eoin (24 November 2014). "Ming appointment for Ballyhea protest founder O'Flynn". Irish Examiner. Archived from the original on 18 March 2015. Retrieved 24 November 2014.