Li hailed from Gaoyang 高陽 (modern Qixian 杞縣, Henan) and had a younger brother called Li Shang 酈商, who was an important military supporter of Liu Bang. Li Yiji was known as a penniless man of letters offering his services to men of importance, yet he was often scolded as madman. Li Yiji was already an old man when he was finally received by Liu Bang.
For his plan to conquer Chenliu 陳留, he was awarded the title of Lord Guangye 廣野君. During Liu Bang's campaigns against the hegemonial king Xiang Yu 項羽, Li Yiji earned special credits for persuading the King of Qi 齊, Tian Guang 田廣, to offer his submission to Liu Bang.
Li stayed at the court of Tian Guang, which proved to be fatal, when general Han Xin 韓信 invaded that region. Tian Guang suspected Li Yiji of secretly plotting against him and had him boiled to death.