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's early career began with training in the printing industry under George Brown in Toronto before moving back to Sarnia where he started a hardware business with his brother John. In 1863, MacKenzie married Agnes Young and also worked as an oil trader in Sarnia, holding a leadership position at the Lambton Loan and Investment Company.