On 15 October 2017, O'Neill guided Na Piarsaigh to a third county final in four seasons. He claimed his second championship as manager following the 1-22 to 2-14 defeat of Kilmallock. On 19 November 2017, O'Neill won a second Munster Championship as Na Piarsaigh manager after a 3-15 to 2-10 defeat of Ballygunner in the final. On 17 March 2018, he guided Na Piarsaigh to a second All-Ireland final, however, his side suffered a 2-17 to 1-17 defeat by Cuala. It was later confirmed that O'Neill had stepped down as manager. On 8 November 2019, O'Neill was ratified as manager of the Galway senior hurling team on a two-year term.