McKenzie was born in Ardross, Scotland, the son of a small tenant farmer, and while young saw the hardships caused by the Highland Clearances.

En route (despite his age) McKenzie witnessed the former inhabitants of the nearby Glencalvie estate huddled together in a graveyard after they had been evicted from their homes by an exploitative landlord.

He commenced a typical rural apprenticeship, starting out as a shepherd before progressing incrementally to run a croft and eventually operating a leasehold farm of his own.

While still relatively young he fathered a daughter (Johan McKenzie, who was born on 23 June 1859) out of wedlock which made his social life awkward.

His skill and experience with farming in the hilly country there, which was very reminiscent to those in Scotland, saw him promoted rapidly and by 1863 he was managing a giant run at Puketapu for Jones.

[1] He was elected to the Bushey Road Board as clerk and treasurer in 1865 and likewise served as secretary on the Palmerston school committee for that same year.

His scrupulousness paid off when he was able to defeat John Douglas, a rich and well-known landowner, who was much better educated than McKenzie and a far more proficient public speaker.