The eldest legitimate son of Uesugi Tomooki of Ōgigayatsu, following his father's death in 1537, though he was still a child, Tomosada led an attack on the Later Hōjō clan in the Tachibana district of Musashi province.
In 1537, after Uesugi Tomooki's death, the eldest legitimate son of Ōgigayatsu, Tomosada, took command and attacked the Later Hōjō clan in the Tachibana district of Musashi province, despite being a child.