Clohessy made his Ireland debut against France in February 1993, during the 1993 Five Nations Championship. His first try for Ireland came against Australia in June 1994. Clohessy missed the 1995 World Cup, but was selected in Ireland's squad for the 1999 Tournament. He was desperately unlucky not to be selected for the 1993 British Lions tour to New Zealand and had to withdraw for the 1997 tour to South Africa due to injury . His last appearance for Ireland was against France in the 2002 Six Nations Championship.