He was the son of Crown Prince Sado (who was put to death when Jeongjo was 11 by his father, King Yeongjo) and Lady Hyegyŏng (who wrote the Memoirs of Lady Hyegyŏng, details her life as the ill-fated Crown Princess of Korea, and as advice and explanations for her grandson about the deaths of his grandfather and so many maternal relatives).

[2] Eight years later Yi San asked to visit Sado's living quarter but his Grandfather King Yeongjo refused.

On 21 February 1764, Yi San became the adoptive son of Crown Prince Hyojang and Princess Consort Hyosun by the order of King Yeongjo.

When he was the Crown Prince, King Jeongjo met Hong Guk-yeong[4] (홍국영; 洪國榮), a controversial politician who first strongly supported Jeongjo's accession and toiled to improve the king's power, but ended up being expelled because of his desire and ambition for power.

[6] The first thing that Jeongjo said to his officials was that he was the son of Jangjo (temple name of Crown Prince Sado) who was executed by the former king.

[9] He also was deeply concerned about the continuing outbreaks of measles epidemics, and among other things supplied free public medicines in an attempt curb the death rates.

[2] During his accession, he also issued a royal decree that his mother, Lady Hyegyŏng, be a Dowager Queen since his father, her husband, was supposed to be the King before him.

From then on, King Jeongjo experienced many turbulent periods, but overcame them with the aid of Hong Guk-yeong,[4] Kim Chong-su.

The primary purpose of Kyujanggak was to improve the cultural and political stance of Joseon and to recruit gifted officers to help run the nation.

Jeongjo favored members of the Soron and Namin party over those of the powerful Noron faction, as a way to establish checks and balances and strengthen royal authority.

In 1791, Jeongjo got a report from Chae Je-gong that the people were having difficulty surviving by selling the fruit of their labor.

This abolished the previous law of Gumnanjeonguoun [ko],[15] which reserved this right exclusively to members of merchant groups in the capital.

In 1800, Jeongjo died suddenly under uncertain circumstances at the age of 47, without seeing much of his life's work come to fruition under his son, Sunjo.

[18] He is buried with his wife, Queen Hyoui, at the royal tomb of Geonneung (건릉; 健陵) in the city of Hwaseong.