Walsh lined out for Waterford in three different grades of hurling over a 19-year period. After making his first appearance for the minor team in April 2000, he later progressed onto the under-21 team as a dual player and won a Munster Championship medal as a footballer in 2003. After one season with the Waterford senior football team in 2002, Walsh made his competitive debut for the Waterford senior hurling team aged 19 in 2003 and enjoyed his first success the following year when Waterford claimed the Munster Championship. He claimed a National League title in 2007 before also claiming a second Munster Championship title later that same season. An All-Ireland Championship runner-up in 2008, Walsh won a third Munster Championship medal in 2010 before collecting a second National League title in 2015. He was an All-Ireland Championship runner-up for the second time in his career in 2017. He announced his retirement from inter-county hurling in October 2019.