Yoshimune succeeded to the post of the shōgun in Shōtoku-1 (1716). His term as shōgun lasted for 30 years. Yoshimune is considered among the best of the Tokugawa shōguns. Yoshimune is known for his financial reforms. He dismissed the conservative adviser Arai Hakuseki and he began what would come to be known as the Kyōhō Reforms.

Although foreign books had been strictly forbidden since 1640, Yoshimune relaxed the rules in 1720, starting an influx of foreign books and their translations into Japan, and initiating the development of Western studies, or rangaku. Yoshimune's relaxation of the rules may have been influenced by a series of lectures delivered before him by the astronomer and philosopher Nishikawa Joken.