Born in Latvia, he immigrated to Israel in 1904, where he served as rabbi of Jaffa. He then became chief rabbi of Jerusalem, subsequently the first Ashkenazi chief rabbi of modern Israel in 1921.

Rav Kook thought the return to Israel marked the beginning of divine redemption. He dreamed of establishing a yeshivah that would present to the student an integrated program of higher Jewish education. And set up a yeshivah in Jerusalem in 1924 (Merkaz ha-Rav) which was unique among yeshivot in its religious philosophy and its positive attitude to Zionism. Kook was a deeply religious mystic whose personal religious experience moved him to be deeply concerned about opposition to religion. Throughout his life he searched for the meaning of religion in the modern world. He refused to see a sharp difference between the sacred and the profane, maintaining that all that was essential to human life was potentially sacred.

Kook was a prolific writer, on philosophical and halakhic subjects.