In 707, there was a major drought, and Emperor Zhongzong summoned Ji to discuss the matter with him. The next day, Wu Sansi had the acting director of the imperial astronomical conservatory, Jiaye Zhizhong submit a report stating that the night before, that the star ''Sheti'' had entered the constellation ''Taiwei Palace'' , symbolizing that a faithful official had entered the palace and met the emperor. Emperor Zhongzong was convinced that it involved his meeting with Ji, and issued an edict that praised Ji for great faithfulness that caused the stars to reflect him, and awarded him with clothes and silk. Later that year, when Emperor Zhongzong's crown prince Li Chongjun, by a concubine, who had been repeatedly insulted by Empress Wei's powerful daughter Li Guo'er the Princess Anle, whose husband was Wu Sansi's son Wu Chongxun , and could not bear such insult, rose in rebellion, killing Wu Sansi and Wu Chongxun and then attacking the palace, Ji was described as one of the officials leading forces to defend against the attack on the palace. Li Chongjun was subsequently defeated and killed in flight. Thereafter, Ji and a associated with Wu Sansi, Zong Chuke, made repeated attempts to implicate the senior chancellor Wei Yuanzhong in the plot, and were eventually able to get Emperor Zhongzong to exile, but not execute, Wei Yuanzhong. Meanwhile, Ji was given the designation ''Tong Zhongshu Menxia Sanpin'' , making him a chancellor ''de facto'', and soon thereafter, he was made ''Shizhong'' -- the head of the examination bureau of government and a post considered one for a chancellor.
In 708, Ji was involved in an incident that would cause Suoge , the chieftain of the Tuqishi , to rebel. Suoge had in 706 succeeded his father Wuzhile , and Wuzhile's subordinate Juechuo Zhongjie had been unwilling to submit to Suoge. Juechuo was, however, unable to prevail over Suoge, and he was set to give up his forces and go to the Tang capital Chang'an, when the Tang general Zhou Yiti suggested to him the idea of bribing Zong and Ji to launch an attack against Suoge. Juechuo did so, and Zong, after Juechuo's bribery, proposed to Emperor Zhongzong the idea of attacking Suoge in alliance with Tufan, which Emperor Zhongzong agreed despite opposition by the general Guo Yuanzhen. Suoge heard of this plan and acted first, successfully attacking several Tang outposts and then sending an envoy to Chang'an to demand that Zong be executed. Subsequently, Guo reported the facts of the situation to Emperor Zhongzong, and Emperor Zhongzong sent a peace envoy to make peace with Suoge and creating him Shisixing Khan. Subsequently, in 709, the censor Cui Wan submitted articles of impeachment against Zong and Ji for corruption that led to disaster on the borders. The protocol at that time required that, as the articles of impeachment were read, that the accused officials step out of the palace and await imperial instructions, but Zong did not do so and, in anger, spoke to Emperor Zhongzong and stated that he was faithful and being falsely accused. Instead of investigating, Emperor Zhongzong ordered Zong and Cui swear to brotherhood with each other, causing the people to give Emperor Zhongzong the semi-derogatory epithet of "Peacemaking Son of Heaven."
In summer 710, Emperor Zhongzong died suddenly -- a death that traditional historians believed to be a poisoning carried out by Empress Wei and Li Guo'er, so that Empress Wei could eventually become "emperor" like Wu Zetian, and Li Guo'er could become crown princess. Meanwhile, however, another son of Emperor Zhongzong's, the Prince of Wen, was named emperor , but Empress Wei retained power as empress dowager and regent. She sent a number of her associates to survey the circuits to make sure that no one would dare rise against her, and Ji Chuna was sent to survey Guannei Circuit . After Ji left the capital Chang'an, a coup led by Emperor Zhongzong's sister Princess Taiping and nephew the Prince of Linzi killed Empress Wei and Li Guo'er, along with a number of their associates. At that time, Ji had reached Hua Prefecture , and was arrested and executed.