He is on the books of Drogheda United and wears shirt number 26. His main role on the pitch is Midfield. His estimated market valuation currently stands at 50K €.

His latest transfer saw him join Shamrock Rovers from Drogheda United via Loan on 2025-11-30.

Over 33 appearances in the Ireland Premier Division 2025, John O'Reilly-O'Sullivan contributed 0 goals and 0 assists, completed 7 key passes from 223 total passes, and posted a passing accuracy of 5.2.