MacKenzie apprenticed in the printing business with George Brown at Toronto before returning to Sarnia where he went into the hardware business with his brother John. MacKenzie married Agnes Young in 1863. He was also an oil dealer in Sarnia and was president of the Lambton Loan and Investment Company.
MacKenzie began his career by learning the printing trade with George Brown in Toronto before moving back to Sarnia, where he started a hardware store with his brother John. In 1863, MacKenzie married Agnes Young, and he also worked as an oil trader in Sarnia, holding the position of president at the Lambton Loan and Investment Company.