The daughter of James Milne, railway clerk and Mary Lee, Mabel Milne was born in Dundee in 1886. She had two older brothers and a younger sister. The family subsequently moved to Perth. She attended Perth Academy.
She went to France in May 1917, where she served with the Territorial Force Nursing Service.

She died of wounds from an enemy aircraft at St Omer in October 1917. She was mentioned in Dispatches (London Gazette 21 Dec 1917) by Sir Douglas Haig for gallant and distinguished conduct in the field.