Seongjong, who became the ninth king of Joseon at the age of 12, initially saw his rule overseen by his grandmother Grand Royal Queen Dowager Jaseong, his biological mother Queen Insu, and his aunt Queen Dowager Inhye. In 1476, Seongjong began to govern independently. His reign, starting in 1469, was a period of relative stability and prosperity, building upon the foundations laid by his predecessors Taejong, Sejong, and Sejo. Seongjong was known for his effective leadership and administrative skills. One of his notable achievements was the completion and implementation of the Grand Code for State Administration, initiated by his grandfather.

Seongjong's reign was also marked by significant developments in the royal court's structure. He expanded the Office of Special Advisors, strengthening the role of this advisory council which also functioned as a royal library and research institute. Additionally, he reinforced the Three Offices – the Office of the Inspector General, the Office of Censors, and the Office of Special Advisors – to ensure checks and balances within the court. In his efforts to create an effective administration, Seongjong appointed skilled administrators without bias towards their political affiliations, bringing liberal scholars to court. His reign saw various innovations and the publication of books on geography, social etiquette, and other subjects beneficial to the populace.

Seongjong's reign, however, wasn't without controversy. His decision to execute Lady Yun, one of his concubines whom he had elevated to queen, for her attempts to poison rivals, would later fuel the tyranny of his successor, Yeonsangun. Additionally, Seongjong enforced social policies such as the "Widow Remarriage Ban" in 1477, which prohibited the sons of remarried women from holding public office. This policy strengthened societal stigmas and had lasting social impacts.

In 1491, Seongjong launched a successful military campaign against the Jurchens on the northern border, continuing Joseon's militaristic stance in the region. Seongjong died in January 1495 and was succeeded by his son, Yi Yung, who became Yeonsangun of Joseon. Seongjong's tomb, Seonneung, is located in Seoul, where he was later joined by his third wife, Queen Jeonghyeon.