Xiao Xin (Chinese: 小辛, born Zi Song, 子颂) was a Shang Dynasty King of China.
In the Records of the Grand Historian he was listed by Sima Qian as the twentieth Shang king, succeeding his older brother Pan Geng (盤庚). He was enthroned in the year of Jiawu (甲午) with Yin (殷) as his capital. He ruled for 3 years, was given the posthumous name Xiao Xin and was succeeded by his younger brother Xiao Yi (小乙).
Oracle script inscriptions on bones unearthed at Yinxu alternatively record that he was the nineteenth Shang king.