Mannie McArthur grew up playing for the Eastern Suburbs RUFC, helping the Warriguls win the premiership in 1901. He then played for one year with Randwick before returning to Eastern Suburbs. Captaining the club in 1908 he was chosen for the Wallabies tour of the British Isles and France, during which time he played in the 1908 London Olympics, helping Australia to a gold medal. He played in 15 of 38 matches during the tour.
Upon returning Down Under, many of his teammates switched to professional rugby league, but McArthur played with Eastern Suburbs until 1914 when World War I suspended most rugby in Australia. After the war McArthur coached the Easts, helping them to the first-grade premiership in 1931. McArthur was a successful insurance broker with New York Life Insurance Group.