On December 7, 1827, he was born in Yamanoguchi Baba, Shitakajiya-cho (Hogiri, Shitakajiya-cho), Kagoshima-jo, Satsuma Province, as the first child of Takamori Kuro SAIGO who was the Go-kanjokata-kogashira (chief of the finance department) (who was renamed Kichibei SAIGO later, and whose salary was about 27 seki).
文政10年（1827年）12月7日、薩摩国鹿児島城下加治屋町山之口馬場（下加治屋町方限）で、御勘定方小頭の西郷九郎隆盛（のち西郷吉兵衛に改名、禄47石余）の第一子として生まれる。