In 1614, the Toyotomi clan rebuilt Osaka Castle. Tensions began to grow between the Tokugawa and the Toyotomi clans, and only increased when Toyotomi began to gather a force of rōnin and enemies of the shogunate in Osaka. Ieyasu, despite having passed the title of Shōgun to his son in 1605, nevertheless maintained significant influence.

The Tokugawa forces, with a huge army led by Ieyasu and shōgun Hidetada, laid siege to Osaka Castle in what is now known as "the Winter Siege of Osaka". Eventually, the Tokugawa were able to force negotiations and an armistice after directed cannon fire threatened Hideyori's mother, Yodo-dono. However, once the treaty was agreed, the Tokugawa filled the castle's outer moats with sand so his troops could walk across. Through this ploy, the Tokugawa gained a huge tract of land through negotiation and deception that they could not through siege and combat. Ieyasu returned to Sunpu Castle, but after Toyotomi Hideyori refused another order to leave Osaka, Ieyasu and his allied army of 155,000 soldiers attacked Osaka Castle again in "the Summer Siege of Osaka".

Finally, in late 1615, Osaka Castle fell and nearly all the defenders were killed, including Hideyori, his mother (Toyotomi Hideyoshi's widow, Yodo-dono), and his infant son. His wife, Senhime (a granddaughter of Ieyasu), pleaded to save Hideyori and Yodo-dono's lives. Ieyasu refused and either required them to commit ritual suicide, or killed both of them. Eventually, Senhime was sent back to Tokugawa alive. With the Toyotomi line finally extinguished, no threats remained to the Tokugawa clan's domination of Japan.