Cowan who was born in Murray Bridge, South Australia, was the eldest son of John Cowan, a pastoralist and parliamentarian, and his wife Elizabeth, née Jones.

He was educated at Prince Alfred College and served in the First Australian Imperial Force.

[4] He also served as the President of the Local Government Association of South Australia.

In 1944, he unsuccessfully contested the House of Assembly seat of Murray.

[5] Cowan was elected unopposed to the Legislative Council on 26 May 1949,[6] and retired during his second term on 28 February 1959.