Born to a Hasidic Jewish family in Polonne in the Russian Empire (today in Ukraine), Mikunis immigrated to Mandatory Palestine in 1921.

During the 1948 Arab-Israeli War, he acted as an emissary to communist countries, seeking to acquire weapons.

In the 1960s, he and Moshe Sneh led a faction within Maki that sought to distance the party from the Soviet Union's anti-Israel stance.

[3] Mikunis lost his seat in the 1969 elections, but re-entered the Knesset in March 1972 as a replacement for Moshe Sneh.

Towards the end of the session, Maki and the Blue-Red Movement merged into Moked and Mikunis lost his seat in the 1973 elections.