His father was a shoemaker named Robert Armour, and his mother was Jean Shaw.
He worked as an auctioneer and was a partner in a merchants firm called Henderson, Armour and Company.
He was appointed as a warden of Trinity House in 1815, a Montreal organisation that regulated the shipping industry along the St. Lawrence River.
[1] In 1816 he was appointed as a commissioner for improving inland navigation and became a partner in the Quebec Steamboat Company.
Later that year he used his children's inheritance from his deceased wife to purchase and invest in the Montreal Gazette.
[1] In 1828, he transferred ownership of the newspaper to his children as collateral while he repaid the money, and continued to operate the company.
The Gazette aligned with the Tory political ideology, printing merchant complaints about the Constitutional Act 1791 and an increase of immigrants from Britain to Canada.
[1] In 1828, Armour published editions of The Montreal almanack, or Lower Canada register, a paper that he created.