Brigadier General Festus Okonkwo is also a member of the UN mission in Liberia.
Before joining Unmil, General Okonko headed Ecomil, the Nigerian-led West African peacekeeping force in the country.
"In a very short time, Ecomil achieved its mandate - which was to stabilise Monrovia and separate the factions in order to allow Unmil to deploy on 1 October.
"We were very happy to be 're-hatted' as Unmil peacekeepers."