Musashi's most famous encounter took place in 1612, against his arch rival Sasaki Kojirō, a swordsman whose skill was reported to be equal to his own. The contest took place on a small island off the coast of Japan. While being rowed out to the dueling site, Musashi fashioned a wooden sword out of an oar. When the two enemies finally met on the beach, Musashi quickly dispatched Kojirō with a well-placed blow to the head using his wooden sword. After that, feeling that he had reached his peak as a swordsman, Musashi retired from the dueling life, though he trained some students and helped to suppress the Shimabara Rebellion in 1637.

According to legend, Musashi wrote his famous work on strategy—Gorin no sho (The Book of Five Rings), which dealt with the martial experience both individually and militarily—on his deathbed. Following its first English translation in 1974, the book was seriously studied by executives in the West in order to better understand Japanese management techniques and strategies.

An artist of suiboku-ga, or sumi-e, (monochrome ink painting), Musashi painted in a powerful and direct style with an amazing economy of strokes. He is particularly remembered for his paintings of birds, such as Koboku meikakuzu (“Shrike Perched in a Dead Tree”) and Rozanzu (“Wild Geese Among Reeds”).