Chen Zhen hailed from Nanyang. When Liu Bei became Governor of Jing, Chen Zhen was hired to serve as a local officer and was stationed in various commanderies. When Liu Bei entered Shu, Chen Zhen remained in his service, where he progressed in rank and soon became Imperial Secretariat at the capital. When Sun Quan declared himself emperor, Liu Shan sent Chen Zhen to offer his congratulations and to form an alliance, which he did, and they also fleshed out their countries’ borders. When he died in AD 235, his son Chen Ji succeeded him.
Chen Zhen first appears in the novel in service to Yuan Shao, though in Sanguozhi it seems his first appearance is in service to Liu Bei. His actions under Yuan Shao are not unlike his duties with Liu Bei, where he performs diplomatic tasks such as delivering Liu Bei's letter to Guan Yu in Luoyang, and meeting with Sun Ce to request aid against Cao Cao. Also in the novel, it was he who suggested to Liu Bei that he meet with the seer Li Yi (李意) while mourning the deaths of his brothers.