William T. Britton is the only representative of Ireland to win a Commonwealth Games* medal. This was his silver for the hammer throw in 1930.
Ireland took part in both the 1930 and 1934 Games. Constitutional changes in 1937 reduced the connection between Ireland and the Crown. They could have taken part in 1938 but did not. There were no Games in 1942 or 1946 because of WW2 and its aftermath, and in 1947 Ireland severed any remaining connection to the Commonwealth.

*Then known as the British Empire Games.