Chen Zhen was from Nanyang Commandery, which is around present-day Nanyang, Henan. When Liu Bei was Governor of the Jing Province in 209, Chen was recruited among Liu Bei's staff an attendant clerk with authority over the various prefectures. Chen Zhen followed Liu Bei into Yi Province. When the conflict was settled in 214, Liu Bei trusted him and made him Commandant of the North District of Shu Commandery (蜀郡北部都尉). Later because the prefecture name was changed he became Administrator of Wenshan(汶山太守), then he was transferred to be Administrator of Jianwei(犍為太守).