Owen specialises in commercial disputes, particularly shareholder and investment disputes, as well as disputes in the financial sector. He has been involved in many high profile property disputes and has product liability defence experience in the pharmaceutical, energy drink, motor and tobacco sectors.
Recent significant work includes advising:
- Horizon Sports Management on the defence of the claim brought against it by golfer Rory McIlroy and the prosecution of its counterclaim.
- Alternative Advantage plc in Commercial Court proceedings for the return of over €100m sub-custodied to Bernard Madoff
- Tesco on its contractual dispute relating to the development of a new district centre store at Carrickmines.
- Davy Stockbrokers both on its successful Supreme Court challenge to a decision by the Financial Services Ombudsman and ongoing defence of Credit Union litigation
- DCC plc through its High and Supreme Court insider dealing action brought by Fyffes plc and the subsequent Inspectorship process
Owen served as a member of the Law Society’s Litigation Committee for six years and is currently a member of the International Bar Association, the Steering Committee of the Commercial Litigation Association of Ireland and DRI Europe.
2025 Legal 500 EMEA
"Owen O'Sullivan is a master strategist who keeps his eyes on the prize and does not lose focus."

2024 Chambers Global
“Owen O'Sullivan is excellent to work with.”

2023 Chambers Europe
“Owen O'Sullivan is an astute lawyer and a calm and steady influence in difficult circumstances.”
