In 551, with the general Hou Jing in control of the imperial government at the capital Jiankang, Hou, wanting to show off his strength, deposed Xiao Dong's granduncle Emperor Jianwen and replaced him with Xiao Dong, the grandson of Emperor Jianwen's older brother Xiao Tong, who was originally the founder Emperor Wu's crown prince.
When Xiao Tong died in May 531, Emperor Wu had considered, pursuant to Confucian principles of succession, creating Xiao Huan crown prince, but ultimately decided against it and created him only the Prince of Yuzhang.
In 551, Hou, after attempting to defeat Emperor Jianwen's brother Xiao Yi the Prince of Xiangdong but being defeated by Xiao Yi's general Wang Sengbian, retreated to Jiankang, and he, believing that his days may be numbered, wanted to take the throne.
In order to show off his power, he deposed Emperor Jianwen and replaced him with Xiao Dong.
When the imperial procession went to Xiao Dong's residence to escort him to the palace, Xiao Dong and his wife Princess Zhang were tending their garden, growing vegetables to supplement their diet in light of the war-induced famine in the capital region.
In spring 552, Wang Sengbian captured Jiankang, forcing Hou Jing to flee.
Before they finished, Zhu's guards grabbed them and threw them into the Yangtze River to drown.