John Miller Dow Meiklejohn was son of John Meiklejohn, an Edinburgh schoolmaster, and was educated at his father's private school. He graduated at Edinburgh University on 21 April 1858, when he was the gold medallist in Latin. At an early age he devoted himself to German philosophy: in 1854, at the age of eighteen, he translated Kant's Critique of Pure Reason which remained the standard english text for over a century. Meiklejohn became a private schoolmaster, first in the Lake district and then in Orme Square and York Place, London. He also lectured and took up journalism, in 1864 acting as a war correspondent in the Second Schleswig War, and being arrested as a spy.
In 1874 Meiklejohn was appointed as assistant commissioner to the endowed schools commission for Scotland, and made educational suggestions in its report. In 1876 Andrew Bell's trustees instituted a chair of the theory, history, and practice of education in St. Andrews University, and Meiklejohn was appointed as the first professor. There he influenced educational ideas at a time when the national system of education was undergoing a reconstruction.
Meiklejohn unsuccessfully contested the Glasgow Tradeston parliamentary consitutency as a Gladstonian liberal in 1886.