In September 1962 he signed for Sunderland for £23,000. Mulhall made 289 appearances and scored 67 goals for Sunderland, and he helped the team to win promotion to the First Division in 1963–64. Mulhall was ever-present that season, as part of a run of 114 consecutive appearances. He won another two international caps, also against Northern Ireland, before moving to South Africa to play for Cape Town City in 1969. He stayed for three seasons before playing one final game for Morton.