Senior Championship and made his first appearance on 25 June in a 1–13 to 0–11 defeat of Bishopstown. Cork Minor and under-21 O'Connell first played for Cork when he was selected for the minor team during the 1995 Munster Championship. He made his first appearance for the team on 28 June when he scored six points from left wing-forward in a 2–14 to 1–03 defeat of Limerick. O'Connell won a Munster Championship medal on 9 July following a 3–18 to 0–10 defeat of Waterford. On 3 September he lined out at left wing-forward in the All-Ireland final against Kilkenny and collected a winners' medal after scoring 1–03 in the 2–10 to 1–02 victory. On 17 July 1996, O'Connell made his first appearance for the Cork under-21 team in a 2–18 to 1–12 defeat of Tipperary. He won a Munster Championship medal on 24 July after scoring four points from right wing-forward in a 3–16 to 2–07 defeat of Clare in the final. O'Connell won a second consecutive Munster Championship medal on 30 July after scoring six points in a 1–11 to 0–13 defeat of Tipperary in the final. On 21 October, he won an All-Ireland from left wing-forward medal following Cork's 3–11 to 0–13 defeat of Galway in the final. Cork dominated the championship again in 1998, with O'Connell winning a third successive Munster Championship medal on 23 August following a 3–18 to 1–10 defeat of Tipperary in the final. He won a second successive All-Ireland medal on 20 September after scoring seven points from left wing-forward in Cork's 2–15 to 2–10 defeat of Galway in the final. It was O'Connell's last game in the grade. Senior O'Connell joined the Cork senior team during the 1998 National League and made his first appearance for the team on 8 March in a 0–16 to 1–08 defeat of Kilkenny. On 17 May, he won a National Hurling League medal as a non-playing substitute following a 2–14 to 0–13 defeat of Waterford in the final. O'Connell was later an unused substitute for Cork during the 1998 Munster Championship and was subsequently dropped from the team. Impressive form at club level earned a recall for O'Connell. He made his championship debut on 13 June and scored eight points from midfield in a 0–24 to 1–15 defeat of Waterford. On 4 July, he won a Munster Championship medal after scoring five points in a 1–15