Born in Ehime Prefecture, Mori graduated from Kyoto University before joining Nikkatsu's Uzumasa studio in 1933. A favorite of the producer Masaichi Nagata, he followed him to Daiichi Eiga and Shinkō Kinema before getting a chance to direct in 1936 with Adauchi hizakurige. When Shinkō Kinema was merged with other studios to form Daiei Film, Mori became one of Daiei's core directors of genre films, making primarily samurai films with stars such as Raizō Ichikawa, Kazuo Hasegawa, and Shintaro Katsu. While not an auteur, he was a solid craftsman in the genre. After Daiei went bankrupt in the early 1970s, Mori continued directing jidaigeki on television. He directed over 130 films in his career. The National Film Center in Tokyo did a retrospective of his works in 2011 in celebration of his centenary.
- Adauchi hizakurige (仇討膝栗毛) (1936)
- Vendetta for a Samurai (荒木又右衛門 決闘鍵屋の辻 Araki Mataemon: Kettō kagiya no tsuji) (1952)
- Tōjūrō no Koi (1955)
- Fighting Fire Fighter (1956)
- Zenigata Heiji: Human-skin Spider (1956)
- Suzakumon (1957)
- Yatarō gasa (1957)
- Inazuma Kaidō (1957)
- The 7th Secret Courier for Edo (1958)
- Hitohada Kujaku(1958)
- Samurai Vendetta (1959)
- Blind Menace (不知火検校 Shiranui kengyō) (1960)
- The Tale of Zatoichi Continues (1962)
- Mori, Kazuo; Kōichi Yamada; Sadao Yamane (1989). Mori Kazuo eigatabi. Tokyo: Sōshisha. ISBN 4-7942-0353-5.