King Pasenadi, also known as Prasenajit, reigned over the kingdom of Kosala from its capital at Savatthi. As brother-in-law to King Bimbisara of Magadha—through the marriage of one of his sisters as chief queen of Magadha—he maintained significant political ties. His own chief queen, Mallika, originally the daughter of a garland-maker, won his favor through her cheerful demeanor after a military defeat. He also married Vasabha Khattiya, a woman of the Sakya clan, with whom he fathered a son, Viḍūḍabha, and a daughter, Princess Vajira. Vajira later married Pasenadi's nephew, King Ajatasattu of Magadha.

An early and devoted follower of the Buddha, Pasenadi regularly sought the Buddha’s counsel on matters of governance, personal conduct, and philosophy. Initially skeptical of the Buddha’s enlightenment due to his youth, Pasenadi was persuaded by the Buddha’s argument that youth should not be underestimated, illustrated through analogies of a warrior, a serpent, a fire, and a monk.

Queen Mallika often guided him in spiritual matters, shaping his policies. When Mallika gave birth to a daughter, Pasenadi expressed disappointment, but the Buddha advised that a wise and virtuous daughter could surpass a son, even raising a future ruler. This counsel helped Pasenadi value his child.

He learned from the Buddha that attachment to loved ones invites sorrow, a truth he grasped upon reflecting on his own affections. The Buddha also taught him the futility of war—that victory breeds hatred and peace arises from abandoning both conquest and defeat.

Pasenadi clashed militarily with his nephew Ajatasattu. After an initial loss, he later captured Ajatasattu alive but, heeding the Buddha’s advice against perpetuating cycles of revenge, released him without seizing his army or wealth.

His reign concluded in tragedy when his son Viḍūḍabha rebelled, forcing Pasenadi to flee Kosala. He died at the gates of Rājagaha, capital of Magadha, in his eightieth year.