Fenlon first played hurling to a high standard as a student at Enniscorty CBS. He lined out in all grades during his time there and won a Leinster Colleges JBHC title in 1987, following a defeat of Callan CBS in the final.[2] Fenlon was also part of the team beaten by 3-06 to 3-02 by Presentation College, Athenry in the subsequent All-Ireland final.[3]
At club level, Fenlon first played for the Rapparees Starlights club as a dual player in the juvenile and underage grades before progressing to adult level. He had his first senior success in 2022 when the club beat Duffry Rovers in a replay to take the Wexford SFC title.[4] Fenlon added a second SFC medal to his collection in 2004 after a defeat of Sarsfields in the final.[5]
Fenlon first appeared on the inter-county scene with Wexford as a member of the minor team in 1991.[6] He later spent an unsuccessful tenure with the under-21 team. Fenlon was still eligible for the under-21 grade when he made his senior team debut in 1993 and quickly became a regular member of the starting fifteen.[7] He won a Leinster SHC medal in 1996, before playing at midfield when Wexford beat Limerick in the 1996 All-Ireland final.[8] Fenlon ended the season with an All-Star award.[9]
A second Leinster SHC medal followed for Fenlon in 1997, when Wexford retained the title after a defeat of Kilkenny.[10] He claimed a third Leinster winner's medal after a defeat of Offaly in 2004.[11] Fenlon also earned selection for the Leinster team and won a Railway Cup medal in 1998.[12] He confirmed his retirement from inter-county hurling in March 2006.[13]