Mentuhotep III was the second and probably the oldest surviving son of Mentuhotep II and his queen Tem.
When entering office he was probably a mature man after the very long reign of his father.
Despite his own time on the throne of a dozen years he has left many remains telling about his deeds and whereabouts but mostly in petty things and few big buildings. He seems to have been engaged in arts and restaurations.
Monuments of his are known from Abydos, El Kab, Armant, el-Tod, Elephantine and Thebes.
He strengthened the borders in the north against intruders from Asia and the Middle East and developed the Red Sea region by maintaining the trade rute to the Red Sea where he founded the harbor town of Kuser.
He built a small shrine to the god Thoth near Deir el Bahri on the west bank of Thebes.