John Mackenzie may refer to:
- Jock Mackenzie (born 1882), Scottish footballer
- Jock MacKenzie (born 1885), Scottish footballer
- John Mackenzie, 9th of Kintail (died 1561), chief of the Clan Mackenzie
- John Mackenzie, Lord MacLeod (1727–1789), Scottish Jacobite and soldier of fortune
- John Randoll Mackenzie (1763–1809), Scottish general and politician
- John Mackenzie (banker) (1787–1854), Provost of Inverness
- John Mackenzie (1806–1848), Scottish scholar of Gaelic literature
- John Mackenzie (missionary) (1835–1899), Scot who championed the rights of Africans in Southern Africa and proposed British intervention to curtail Boer influence
- John Mackenzie (colonial settler) (1793–1857), veteran of Peninsula War and War of 1812, and a pioneer colonial settler of New South Wales, Australia
- John MacKenzie (doctor) (died 1837), Scottish army surgeon and physician
- John Stuart Mackenzie (1860–1935), British philosopher
- John Joseph Mackenzie (1865–1922), Canadian pathologist
- John Mackenzie (VC) (1869–1915), Scottish recipient of the Victoria Cross
- John Mackenzie (sailor) (1876–1949), British Olympic sailor
- John MacKenzie (Medal of Honor) (1886–1933), American Medal of Honor recipient
- John Mackenzie (film director) (1928–2011), Scottish film director
- John Ashton MacKenzie (1917–2010), U.S. federal judge
- John W. Mackenzie (died 1914), Canadian missionary to Vanuatu
- John Drew MacKenzie (died 1918), master craftsman and instructor of the Newlyn Copper school in Cornwall, UK
- John M. MacKenzie (born 1943), British historian of imperialism
- John Mackenzie, 5th Earl of Cromartie (born 1948), current chief of Scotland's Clan Mackenzie
- John MacKenzie (mountain guide) (1856–1933), Britain's first professional mountain guide
- John Archie MacKenzie (born 1934), member of the Nova Scotia House of Assembly
- John Kenneth MacKenzie (1850–1886), English medical missionary to China
- John Muir Mackenzie (1854–1916), acting governor of Bombay
- John Edwin MacKenzie (1868–1955), Scottish chemist
- John Noble MacKenzie (1914–1993), New Zealand flying ace of the Second World War
- Johnny MacKenzie (1925–2017), Scottish footballer (Partick Thistle, national team)