Zhenjin (Chinese: 真金; 1243 – 1285^[1] or January 5, 1286), also Jingim, Chinkim, or Chingkim (Mongolian: Чингим/Chingim), was the second son of Kublai Khan and grandson of Tolui. Also, the founder of the Yuan dynasty. He was designated as the Crown Prince (皇太子) by Kublai Khan in 1273, and became the head of the Central Secretariat (Zhongshu Sheng). The North Chinese Buddhist monk Haiyun gave him the name Zhenjin ("True Gold") when he was born in 1243. He was also known as a strong supporter of Confucianism. When a Confucian-trained official in the South proposed that Kublai abdicate in favor of Zhenjin in 1285, Kublai was angered. Zhenjin died on 5 January 1286, eight years before his father Kublai Khan.

According to the History of Yuan, he died of alcoholism. However, it may not have been as simple as merely drinking too much. It also stated that shortly before his death, some ministers of the court wanted to propose that Kublai Khan abdicate his throne to Zhenjin on account of old age and because Prince Zhenjin was highly respected throughout the empire. However, Prince Zhenjin tried to prevent this from happening. Unfortunately, Kublai Khan found out anyway and was furious, which terrified Zhenjin and may have led him to overdrink. Distressed by his death, Kublai Khan made Zhenjin's son Temür the new Crown Prince, and Temür succeeded Kublai Khan in 1294 and became the Temür Khan or Emperor Chengzong.

"Prince Chinkin" is a central character in the 1982 American-Italian miniseries Marco Polo, where he was portrayed by actor Junichi Ishida.^[4]

"Prince Jingim" is also a main character of the 2014 Netflix original series Marco Polo, where he is portrayed by Remy Hii.^[5]