Australian boys’ singles champion in 1958, Mulligan is best remembered for reaching the Wimbledon singles final in 1962 where he lost to fellow Australian Rod Laver in straight sets.

He won the Italian Championships three times, in 1963, 1965 and 1967. Mulligan was runner-up at the Australian doubles championships in 1961.

He never made the Australian Davis Cup squad. Later, he moved to Italy where he married and became a businessman, earning the nickname “Martino Mulligano”.

He played four ties for Italy’s Davis Cup team in 1968, holding a 9-2 win–loss record.