Kirby helped Waterford reach the semi-final of the FAI Cup in 2000–01. In the quarter-final, his shot was pushed over the bar by a Cobh Ramblers defender, and he converted the resulting penalty to give Waterford a 1–0 win. The semi-final, against Longford Town, went to a replay. Kirby came close to scoring, and was named man of the match as he had been in the quarter-final, but the tie was settled by a penalty kick in favour of Longford. He was named in the PFAI First Division Team of the Year for 2001, and shortlisted for the First Division Player of the Year award.