After two lackluster championship campaigns by Cork in 1987 and 1988, Mulcahy was dropped from the team in 1989. Glen Rovers's club success at the end of that year paved the way for a return to the Cork team when the club nominated Mulcahy for the county captaincy in 1990. An injury resulted in him missing Cork's successful provincial campaign, however, he made his first championship appearance in over two years in Cork's All-Ireland semi-final defeat of Antrim. The subsequent All-Ireland final on 2 September 1990 pitted Cork against Galway for the second time in four years. Galway were once again the red-hot favourites and justified this tag by going seven points ahead in the opening thirty-five minutes thanks to a masterful display by Joe Cooney. Cork fought back with an equally expert display by Mulcahy. The game was effectively decided on an incident which occurred midway through the second half when Cork goalkeeper Ger Cunningham blocked a point-blank shot from Martin Naughton with his nose. The umpires gave no 65-metre free, even though he clearly deflected it out wide. Cork went on to win a high-scoring and open game of hurling by 5–15 to 2–21. As well as winning a third All-Ireland medal Mulcahy also had the honour of lifting the Liam MacCarthy Cup.