Ryan made his first impression on the inter-county scene in 2008 as a member of the Kilkenny under-21 team. He won his first Leinster medal that year as Kilkenny trounced Offaly by 2–21 to 2–9. Ryan later added an All-Ireland Under-21 Hurling Championship medal following a 2–13 to 0–15 defeat of Tipperary in the decider. Kilkenny retained the provincial under-21 crown in 2009 following a 2–20 to 1–19 defeat of Dublin, giving Ryan a second Leinster medal in that grade. Kilkenny subsequently had the chance to retain the All-Ireland crown, however, Ryan's side faced a narrow 0–15 to 0–14 defeat by first time champions Clare. Ryan joined the senior team after the 2011 National Hurling League and was a member of the panel for the subsequent Leinster and All-Ireland victories. The 2012 National Hurling League was Ryan's first full campaign with the Kilkenny senior team, however, a knee cartilage injury after the first two rounds resulted in him facing a month-long lay-off. He was later restored to the starting fifteen and was once again a member of the panel as Kilkenny claimed All-Ireland honours. Ryan was a regular member of the starting fifteen in 2013. He won a National Hurling League medal on the field of play that year as Kilkenny defeated Tipperary by 2–17 to 0–20. He finished off the campaign by being named GAA-GPA Hurler of the League. Ryan made his senior championship debut on 9 June 2013 in a 0–26 to 4–9 defeat of Offaly. In February 2014 Ryan was appointed captain of the Kilkenny senior hurling team. In the League Final he was introduced as a substitute during the team's 2–25 to 1–27 extra-time defeat of Tipperary in the final. It was his second National League medal while he also had the honour of lifting the cup. He made a number of appearances in the championship, including in Kilkenny's 0–24 to 1–9 trouncing of Dublin in which he claimed his first Leinster medal on the field of play. On 7 September 2014, Kilkenny faced Tipperary in the All-Ireland decider. In what some consider to be the greatest game of all-time, the sides were level when Tipperary were awarded a controversial free.