In 1896, he travelled west to British Columbia's Slocan Valley where he mined several claims and became a prominent member of the Western Federation of Miners, serving one year as president of the union.

After a stint in real estate, he and a partner purchased the Star Clothing Company at Queen and Gore Streets where he became a successful merchant.

After serving as secretary-treasurer of the public school board from 1915 to 1916, he was acclaimed as a city alderman in 1918 and won election in 1919.

Farquhar was a candidate for the Progressive Party in Algoma West in the 1921 federal election but finished third with 27 per cent of the vote.

In 1926, Farquhar entered provincial politics and was elected to represent Manitoulin in the Legislative Assembly of Ontario as a United Farmers member.

On 10 September 1948, Prime Minister William Lyon Mackenzie King appointed Farquhar to the Senate so that his new Minister of External Affairs Lester B. Pearson could contest the by-election in the relatively safe Liberal riding of Algoma East and enter the House of Commons.

He married his second wife, Kathleen's younger sister, Florence Amy Wiber in Little Current on Manitoulin Island in October 1914.

His first son, Stanley, would follow his father's career path into public service, representing the riding of Algoma—Manitoulin in the Legislative Assembly of Ontario from 1963 to 1971.

Farquhar died on 24 December 1962 at the age of 87 and was interred in Mindemoya Cemetery on Manitoulin Island.