Club O'Neill plays his club football with his local club called
Ballyclough.
Minor and under-21 Football O'Neill first came to prominence on the inter-county scene as a member of the
Cork minor football team in 2005. He made his debut as a substitute in the first round of the provincial championship against
Limerick. Cork won that game and later qualified for a Munster final showdown with
Kerry. By that stage of the championship O'Neill had established himself as a key member of the starting fifteen. In an exciting game he ended up as Cork's top scorer with 2–3 and was a large factor in the 3–8 to 1–11 victory. It was also his first
Munster minor winners' medal. Cork, however, were defeated by
Offaly in the subsequent All-Ireland quarter-final. Cork's defence of their provincial minor title ended with a semi-final defeat by
Tipperary. That same year O'Neill was drafted onto the Cork under-21 football team. He came on as a substitute in the Munster semi-final victory over
Clare, however, he played no part in the subsequent Munster final triumph and All-Ireland semi-final defeat. In 2006 O'Neill was still eligible for the Cork minor team. In spite of scoring a goal and a point, Cork's defence of their provincial minor title ended with a semi-final defeat by
Tipperary. Once again, O'Neill was drafted onto the Cork under-21 football team. He came on as a substitute in the Munster semi-final trouncing of Tipperary, however, his services were not required for the subsequent Munster final triumph and All-Ireland final defeat. By 2007 O'Neill was regularly a part of the starting fifteen of the Cork under-21 team. He lined out in the provincial decider that year against Tipperary and a high-scoring and exciting game developed. O'Neill had an uncharacteristic quiet day and was held scoreless. In spite of that Cork still won by 3–19 to 3–12 and he added a
Munster under-21 winners' medal to his collection. Cork later manoeuvred through the All-Ireland series and reached the All-Ireland final against
Laois. Another close and exciting game of football developed as neither side took a decisive lead. O'Neill chipped in with a goal and a point, to help his side to a narrow 2–10 to 0–15 victory. It was his first
All-Ireland winners' medal at under-21 level. After surrendering their provincial under-21 crown in 2008, Cork bounced back in 2009 with O'Neill as captain. The Munster final that year pitted Cork against Tipperary and, once again, a close game was the result. At the full-time whistle 'the Rebels' did just about enough to secure a 1–9 to 2–5 victory. It was O'Neill's second Munster under-21 winners' medal on the field of play. For the second time in three years Cork subsequently reached the All-Ireland final.
Down provided the opposition on that occasion and there was little to separate the two sides for much of the game. It took a late goal from
Colm O'Driscoll to secure a 1–13 to 2–9 victory for Cork. Not only did O'Neill collect a second All-Ireland under-21 winners' medal, but he also had the honour of collecting the cup on behalf of his county.
Hurling O'Neill also played
hurling at minor and Under-21 level with
Cork. In 2006 he was part of the
Cork side that won the
Munster Minor Hurling Championship after a win over
Tipperary in the final. In 2007 he won a
Munster Under-21 Hurling Championship after a win over
Waterford in the final.
Senior In 2009 O'Neill joined the Cork senior football panel in time for the start of the championship. He made his senior debut as a substitute for
James Masters against
Waterford in the provincial quarter-final. O'Neill also came on as a substitute in Cork's next game against
Kerry and immediately scored a 45-metre free to give Cork a one-point lead. Kerry, however, equalised and forced a draw. The replay saw Cork defeat their old enemy; however, O'Neill played no part in the game. He was introduced as a substitute again in the subsequent Munster final against Limerick, closely followed by his club-mate
Paul O'Flynn. The game looked to be going away from Cork, however, 'the Rebels' fought back with O'Neill chipping in with a point. It was a vital score as Cork went on to win by a point on a score line of 2–6 to 0–11. It was O'Neill's first
Munster winners' medal in the senior grade. Subsequent defeats of
Donegal and
Tyrone saw Cork qualify for an All-Ireland final showdown with Kerry. Cork were surprisingly named as favourites, however, this tag appeared to be justified when Cork led by 1–3 to 0–1 early in the opening half, courtesy of a goal and a point from O'Neill. The Kerry team stuck to their gameplan, helped in no small part by a Cork side that recorded fourteen wides. At the final whistle Kerry were the champions again by 0–16 to 1–9. In 2010 O'Neill was used as an impact sub rather than as a member of the starting fifteen. A defeat by Kerry in a replay of the provincial semi-final resulted in Cork being exiled to the All-Ireland qualifiers. After negotiating their way through a difficult series of games, Cork defeated
Dublin to qualify for their third All-Ireland final in four years.
Down provided the opposition on that occasion in the first meeting between these two teams since 1994. Cork got off to a lightning start, however, they eased off and trailed by three points at the interval. O'Neill didn't start, however, when he came on as a substitute he immediately caused problems in the full-forward line.
Paul Kerrigan got his sole point of the match to put 'the Rebels' ahead for the first time in fifty minutes after surrendering the lead in the fifth minute. Cork stretched the lead to three points, however, Down fought back. At the full-time whistle Cork were the champions by 0–16 to 0–15 and O'Neill picked up an
All-Ireland winners' medal. In 2011, O'Neill injured his cruciate ligament while playing for Cork against
Galway. It was his second such injury having also done it in while playing for his club Ballyclough in 2008. ==Career statistics==