Born in Grand River, Nova Scotia, the son of Donald and Annabella (Murchison) Finlayson, Finlayson was educated at the Sydney Academy and Dalhousie University where he received a Bachelor of Arts degree in 1893 and a Bachelor of Laws degree in 1895.

He sat in the Nova Scotia House of Assembly from 1897 to 1904.

He was very passionate about law and wished to be a lawyer for no other reason than justice.

In 1908, he was appointed judge of the County Court, District No.

7 and was appointed surrogate judge in Admiralty for the Island of Cape Breton in 1911.