Emperor Zhezong of Song, personal name Zhao Xu, was the seventh emperor of the Song dynasty of China. His original personal name was Zhao Yong but he changed it to "Zhao Xu" after his coronation. He reigned from 1085 until his death in 1100, and was succeeded by his younger half-brother, Emperor Huizong, because his son died prematurely.

The Song dynasty was an imperial dynasty of China that ruled from 960 to 1279. The dynasty was founded by Emperor Taizu of Song, who usurped the throne of the Later Zhou dynasty and went on to conquer the rest of the Ten Kingdoms, ending the Five Dynasties and Ten Kingdoms period. The Song often came into conflict with the contemporaneous Liao, Western Xia and Jin dynasties in northern China. After retreating to southern China following attacks by the Jin dynasty, the Song was eventually conquered by the Mongol-led Yuan dynasty.