It is not known when Tan Daoji was born, but what is known is that he lost his parents early, and was said to be appropriate in his deeds even as a young orphan, being respectful to his older brothers and sisters.

He continued to participate in various campaigns, including assisting Liu Yu's brother Liu Daogui (劉道規) against invading Later Qin and Western Shu forces commanded by Gou Lin (苟林) and Huan Xuan's cousin Huan Qian (桓謙) in 410 and battling Xu Daofu (徐道覆), the brother-in-law of the warlord Lu Xun (盧循).

When Emperor Wu grew ill in 422, he entrusted Liu Yifu to Xu Xianzhi, Fu Liang, Xie Hui and Tan, and he died soon after.

Unlike Xu, Fu, and Xie, however, Tan did not remain at the capital Jiankang or involve himself with the operations of the imperial government, but became the governor of Southern Yan Province (南兗州, modern central Jiangsu).

In light of his victory, Emperor Wen promoted Tan to greater titles and made him the governor of Jiang Province (江州, modern Jiangxi and Fujian).

When Emperor Wen launched a major campaign against Northern Wei in 430 to try to regain provinces south of the Yellow River, Tan was not in command of the army—Dao Yanzhi (到彥之) was.

When it did so in winter 430, Dao retreated after Luoyang and Hulao fell, leaving Huatai (滑台, in modern Anyang, Henan) and its commanding general Zhu Xiuzhi (朱脩之) under Northern Wei siege and totally without support.

At that time, Tan was already on the dock ready to depart for Jiang Province, and Liu Yikang summoned him back to Jiankang and arrested him.

Emperor Wen then issued an edict falsely accusing Tan of preparing treason and executed him with his sons, but spared his grandsons.

Emperor Wen also killed two of Tan's trusted generals, Xue Tong (薛彤) and Gao Jinzhi (高進之), who were capable soldiers and compared by their admirers to Guan Yu and Zhang Fei.