Boaz was born in Jerusalem on 6 June 1927 to David and Sarah. In 1929, the family moved to Tel Aviv. Boaz finished his high school studies in Gymnasium Herzliya in 1944, and he joined the Jewish Settlement Police and the Hagana. In 1946, he began studying history and sociology in Jerusalem’s Hebrew University. The inaction of the Hagana in response to the British oppression, particularly after the explosion at the King David Hotel, caused him to leave the Hagana and join Lehi a year later. Then he travelled to the United States and began to operate in the Lehi branch there.
As the War of Independence began, he abandoned his studies and moved to full-time duty with the American branch of Lehi, until it was disbanded.
Boaz returned in 1951. He joined the Canaanite Movement for a short time, but he left because of ideological disputes. In 1954, he began writing for Haaretz. In 1957, he joined Natan Yellin-Mor, Uri Avneri and others in establishing the Semitic Action Movement. Together, they published the biweekly Etgar. In 1964, he moved from Haaretz to Yedioth Ahronoth. Together with Amos Kenan, Dan Ben-Amotz and Hayim Hefer, he published the satirical supplement Zippor HaNefesh. He became a theater critic and senior publicist for the newspaper. In 1971-1972, he was the acting director of the Beit Tzvi School of Theater Arts in Ramat Gan. In 1972-1974, he was a member of the board of the Council for Culture and Art. At this time, he founded, in 1973, the Exceptional Literature Translation Project, dedicated to translating the best of world literature into Hebrews. In 1975, he published A Measure of Freedom (a philosophical treatise), published by Poalim. In 1988, he published A National Accounting (Dvir Press), dedicated to the critical analysis of Zionism and Zionist thought in Jewish history. In 1995, the book was translated into English (University of Indiana Press) and Arabic (University of Cairo Press). In 1992, he retired from Yedioth Ahronoth, and he started preparing a collection of his works.
In 1948, Boaz married Miriam Rubinstein, and they had two sons: Gilead (born 1955) a playwright, and Yoav (born 1957), a scientist.