Born in 1579 as the third son of Tokugawa Ieyasu in Totomi Province. During the Sekigahara Campaign of 1600, he was delayed besieging Sanada Masayuki's Ueda Castle on the Nakasendo road and missed the decisive battle entirely—a blunder that infuriated Ieyasu. Nevertheless, in 1605 he was appointed the 2nd Tokugawa shogun. As shogun, he promulgated the Buke Shohatto (Laws for the Military Houses) and the Kinchu narabini Kuge Shohatto (Laws for the Imperial Court and Nobility), establishing firm control over daimyo and the court. He aggressively attaindered tozama daimyo, consolidating the bakuhan system. In 1614–15, he commanded forces at the Osaka campaigns that destroyed the Toyotomi. He passed the shogunate to Iemitsu in 1623 but retained real power as ogosho. He died on January 24, 1632, at age 54.

Earnest and meticulous. He lacked his father Ieyasu's military genius, but excelled at legal institution-building and political governance, solidifying the shogunate's foundations. He was also famously henpecked by his wife, Go.

Often dismissed as mediocre for his Sekigahara tardiness, his true legacy lies in building the legal and institutional framework—including the Buke Shohatto—that sustained 260 years of Tokugawa rule. He was the administrator who institutionalized the peace his father won.