John MacKenzie (July 7, 1886 – December 26, 1933) was a sailor in the United States Naval Reserve and a recipient of the Medal of Honor.

Born at Bridgeport, Connecticut, MacKenzie enlisted in the Navy at Springfield, Massachusetts, on December 20, 1902, and had attained the rate of Coxswain before his discharge on July 6, 1907.

He engaged in the auto accessory business in Springfield, but reenlisted in the Navy in 1917, when the United States entered World War I.

While serving on board USS Remlik (SP-157) during a storm in the Bay of Biscay, MacKenzie observed a depth charge adrift on the ship's after deck.

At great risk to his life, he took prompt and effective action to secure the explosive weapon, thus preventing the "probable loss of the ship and the entire crew".