A Conservative in party allegiance, Nelson Spencer was an Orangeman,[4] and in 1910, he belonged to Carnduff, Saskatchewan, Loyal Orange Lodge No.1561 where he served as the County Master for that jurisdiction.

During the war, he was given command of the newly created 175th 'Medicine Hat' Battalion and appointed to the rank of lieutenant-colonel.

[6] Spencer ran for a seat in the Canadian House of Commons as the Conservative candidate in a 1921 by-election in the Medicine Hat federal electoral district held after the death of Arthur Lewis Sifton.

He was elected in the riding of Vancouver City and spent one term in office for the British Columbia Conservative Party.

Spencer later ran as an independent for mayor of Vancouver after losing the Non-Partisan Association nomination in 1937.