Hartnett first played Gaelic football at juvenile and underage levels with the Dr. Crokes club in Killarney.
Hartnett later won two Munster SCFC titles and was at full-back when Dr. Crokes beat Thomas Davis in the 1992 All-Ireland club final.
[1] Hartnett first appeared on the inter-county scene for Kerry as a member of the minor team in 1981.
Hartnett made his only championship appearance when he lined out at full-back in a Munster semi-final defeat of Limerick in 1989.
He was part of the Dr. Croke's management team when they won the Kerry SFC title in 2000.