In 1984, Mullins was back in yet another county final. Na Fianna provided the opposition, however, St. Vincent's engineered a win and Mullins added a fifth winners' medal to his collection in that competition. He later collected a third Leinster club winners' medal following a ten-point win over Wicklow champions Tinahely. The subsequent All-Ireland club final pitted St. Vincent's against Castleisland Desmonds of Kerry. The game has gone down in history as one of the most tense championship deciders of all-time that featured a dramatic finish. With two minutes left Mullins's side had a 0–7 to 1–2 lead. A line ball by Castleisland's Willie O'Connor found Donie Buckley who sent the ball into the net. St Vincent's had no time to launch a comeback and the Kerrymen secured a remarkable 2–2 to 0–7 victory.