Miakotin was educated at the Kronstadt gymnasium and the University of Saint Petersburg, where he studied history and philology.
In the 1890s Miakotin was associated with the 'Legal Populist' movement and contributed to the liberal journal Russkoe Bogatstvo (Russian Wealth), becoming a member of its editorial board in 1904.
He was involved in the liberal 'banquet campaign' of 1904 (modelled on the French oppositional banquets organised on the eve of the 1848 revolution) and was arrested several times.
He also briefly joined the Socialist-Revolutionary Party but rejected its adoption of terrorism and the influence of Marxism on its leading theoreticians (V.M.
Rusanov et al.) In 1906, Miakotin belonged to the narodnik group which broke with the PSR and founded the Popular Socialist Party (NSP).
He supported the February Revolution of 1917, became a member of the central committee of the NSP and helped merge it with the Trudoviki.
He supported a liberal-socialist coalition of "all democratic forces" and a continuation of the war effort, long after this had ceased to be a popular position even among moderate socialists.