Carlow 1-16 Mayo 0-17
A 71st-minute Robert Foley goal decided this Castlebar clash and shot Carlow through to their second Christy Ring Cup final in three years.
Mayo held a 0-10 to 0-06 interval lead with Adrian Freeman scoring five points for the hosts, who finished the half strongly.
However, Rory Dunbar grabbed a trio of scores for Carlow on the restart to cut the gap to the minimum.
Mayo kept in front, and led by a single point as injury-time approached until Foley's goal stole victory.