Club Dunphy enjoyed a highly successful club hurling career with
Mooncoin that spanned more than twenty years. In 1916 he won his first
club championship winners' medal following a victory in a replay over fierce rivals
Tullaroan. The club championship was severely hampered over the next six seasons, however, on its resumption Mooncoin faced defeat in the finals of 1923 and 1926. Mooncoin emerged as a major force in club hurling in the late 1920s, winning three successive county championships between 1927 and 1929. Dunphy captained the side for the last two of these victories. That great Mooncoin team began to break up by the 1930s, however, Dunphy continued to play for the team well into his forties. He captured two more club championship winners' medals in 1932 and 1936, a full twenty years since his first championship title. It was Mooncoin's last county title for almost thirty years.
Inter-county Dunphy first came to prominence on the inter-county scene as a member of the
Kilkenny senior team in the early 1920s. In 1922 he was captain of the side when he captured his first
Leinster title following a defeat of
Dublin. Dunphy later lead his men out in
Croke Park for an All-Ireland final meeting with
Tipperary. With three minutes left to play Tipp were leading by three points, however,
Paddy Donoghue and
Dick Tobin of Kilkeny scored two decisive goals to seal a 4-2 to 2-6 victory. Dunphy captured his sole
All-Ireland medal that day and had the honour of accepting the trophy on behalf of his team. It would be forty-five years before Kilkenny would beat Tipp in the championship again. Dunphy won a second Leinster medal in 1923, however,
Galway defeated the reigning All-Ireland champions at the semi-final stage of the championship. 1925 saw Dunphy win a third provincial title, however, Galway put an end to Kilkenny’s championship hopes at the All-Ireland semi-final stage once again. In 1926 Kilkenny defeated
Offaly to give Dunphy his fourth and final Leinster medal. He later lined out in a second All-Ireland final with
Cork providing the opposition on this occasion. Snow covered Croke Park on the day of the final as Cork went on to win the game on as core line of 4-6 to 2-0. Dunphy’s involvement with the Kilkenny team ended in 1930.
Inter-provincial Dunphy also lined out for
Leinster in the inter-provincial hurling competition. In 1927 he captained Leinster to a 1-11 to 2-6 victory over
Munster in the inaugural final of the
Railway Cup. That game is remembered as one of the finest contests in the history of hurling. Dunphy also lined out for Leinster in 1928 and 1930; however, victory went to Munster on both occasions. ==Personal life and death==