The 2008 All-Ireland Under-21 Hurling Championship was the 45th staging of the All-Ireland Under-21 Championship since its establishment by the Gaelic Athletic Association in 1964. The championship ran from 28 May to 14 September 2008.
Galway entered the championship as the defending champions, however, they were beaten by Kilkenny in the All-Ireland semi-final.
The All-Ireland final was played on 14 September 2008 at Croke Park in Dublin between Kilkenny and Tipperary in what was their ninth meeting in the final overall and a first meeting in the final in two years. Kilkenny won the match by 2-13 to 0-15 to claim their 11th championship title overall and a first title in two years. This win completed a Grand Slam of hurling titles for Kilkenny in 2008.
Kilkenny's Richie Hogan was the championship's top scorer with 3-27.