He hailed from Wanqu 宛朐 (modern Dongming 東明, Shandong) and became a follower of Liu Bang when the latter rose an army against the Qin dynasty 秦 (221-206 BCE) in 209. He accompanied Liu Bang as Special General (tejiang 特將) and was given the title of marquis after the conquest of the Qin capital Xianyang 咸陽 (modern Xianyang, Shaanxi).
During the war against Xiang Yu 項羽, Chen Xi was mobile corps commander (youji jiangjun 游擊將軍) and was appointed gentleman of the interior (langzhong 郎中). He took part in the campaigns against the kingdoms of Dai 代 and Yan 燕. After Lu Bang became emperor, Chen Xi was made Marquis of Yangxia 陽夏侯 and was appointed counsellor to the Prince of Zhao 趙, a position in which he was to control a great part of the north of the empire.
Liu Bang, fearing a rebellion, had him investigated and thereby provoked Chen Xi's uprising. Staffing his army with cavalry units of Xiongnu 匈奴 origin, he proclaimed himself King of Dai. Yet his army was crushed by general Wang Ling 王陵, and Chen Xi was killed.