The 15th and last shōgun of the Ashikaga Shogunate (r. 1568–1573), younger brother of 13th Shōgun Ashikaga Yoshiteru. After his brother's assassination, he renounced his Buddhist vows and was installed as shōgun by Oda Nobunaga, who restored him to Kyoto. As Nobunaga's grip on power grew, Yoshiaki resisted and organized an anti-Nobunaga coalition. In 1573, he was expelled from Kyoto by Nobunaga (Battle of Makishima Castle) and stripped of the shogunal title. He continued to maintain shogunal functions at Tomo in Bingo Province (present-day Tomonoura, Fukuyama, Hiroshima) with Mōri support—the so-called "Tomo Shogunate"—and persisted in anti-Nobunaga activities. After the Honnō-ji Incident he reconciled with Toyotomi Hideyoshi and in 1588 received the court rank of Minister of Punishments. He died in 1597 at the age of 61. His turbulent life symbolizes the end of the Ashikaga Shogunate and the chaos of the late Sengoku period.

A politician marked by tenacious attachment to authority and a degree of detachment from political reality. He sought to use various powers to preserve the shogunal title but was repeatedly outmaneuvered by towering figures such as Nobunaga and Hideyoshi. Yet he also displayed a stubborn determination to cling to the title of shōgun until the very end.

As the last member of the Ashikaga shogunal line, he is a symbol of the end of the Muromachi period. The "Tomo Shogunate" attracts historical attention as the shogunate's final form. Historic sites associated with Yoshiaki remain at Tomonoura (Fukuyama City) and serve as regional historical tourism resources.