In the middle of the "Kaiyuan" era (712-741) of Emperor Zhongzong's nephew Emperor Xuanzong, Li Shizhi became the prefect of Tong Prefecture (通州, in modern Beijing). He was known for being able, and after the imperial attendant Han Chaozong () surveyed the region, Han recommended him to Emperor Xuanzong. He thereafter successively served as the commandant at Qin Prefecture (秦州, roughly modern Tianshui, Gansu), the prefect of Shan Prefecture (陝州, roughly modern Sanmenxia, Henan), and then mayor of Henan Municipality, to which the eastern capital Luoyang belonged. It was said that Li Shizhi's governance was simple and straightforward, and that he did not dwell on details, to the relief of the officials and people under him. While at Luoyang, he was responsible for building three major levees that alleviated flooding problems that plagued Luoyang, and when a monument was subsequently erected to commemorate his contributions, Emperor Xuanzong had his son Li Lin () the Prince of Yong write the text and Li Ying the Crown Prince write the heading, a great honor for Li Shizhi. Li Shizhi later served as "Yushi Daifu" (), the chief imperial censor.