Before Israel's independence in 1948, he served as Chief of Staff of Haganah, the main Zionist paramilitary organization that operated for the Yishuv in the British Mandate for Palestine.

Yisrael Balashnikov (later Galili) was born in the town of Brailiv in the Russian Empire (now Ukraine).

He was appointed Chief of Staff of the Haganah in 1946, and served in that capacity until June 1948 when he was removed by David Ben-Gurion in what was called the "Generals' Revolt".

He served in the first Knesset from 1949 to 1951, and then again from 1955 until 1977, first on behalf of the Mapam party, before being part of the split that formed Ahdut HaAvoda and later merged into the Alignment.

Victor John Ostrovsky, a self-proclaimed former katsa (case officer) for the Israeli Mossad (foreign intelligence service) claimed in his book By Way of Deception that Galili had a lengthy affair with Golda Meir who was some 13 years his senior.