Belonging to the Kajuji line of the Northern (Hokke) Fujiwara, they were a middle rank aristocratic family until the mid-Kamakura Period, when Shigefusa Kajuji was put in charge of Uesugi no Sho in Ikaruga District of Tanba Province (present-day vicinity of Uesugicho, Ayabe City, Kyoto Prefecture), thereby acquiring the surname of Uesugi.
藤原北家勧修寺流の流れを汲み、鎌倉時代の中頃まで京都の中級公家の家柄であった、重房の代に至って丹波国何鹿郡上杉庄（うえすぎのしょう、現在の京都府綾部市上杉町周辺）を領したことにより上杉を名字とした。