 He was part of the team that won the 1995 Ulster Minor Championship and finished runners-up to Westmeath in that year's All-Ireland Minor final.He was instrumental in Derry's run in that Minor Championship, including scoring 1–07 (10) against Down in the Ulster final and scoring a dramatic last minute goal which helped Derry beat Galway by a point in the All-Ireland semi-final.Muldoon reached the Ulster Under-21 Football Championship final with Derry Under-21s in 1996, but were defeated by Cavan.