He was born in South Yarra to judge William Gilbert Stewart McArthur and Margaret Rutherford Macpherson.
He attended Geelong College before studying at the University of Cambridge, where he received a Bachelor of Arts.
During World War I he served in the Royal Field Artillery, and in 1917 he lost his leg at the Battle of Menin Road.
He was called to the bar in 1929, but in 1934 left his practice to manage his father's property near Camperdown, which he inherited the next year.
In 1931 he was elected to the Victorian Legislative Council as a United Australia Party member for South Western Province.