Brigadier Nunoo-Mensah was appointed Chief of Defence Staff by the Armed Forces Revolutionary Council government in 1979.

[4] Nunoo-Mensah was retired in November 1979 by the People's National Party government of Dr.

He was the campaign manager for Nana Addo Dankwa Akufo-Addo's bid for nomination as the party's candidate for the Ghanaian presidential elections in 1998.

[citation needed] Nunoo-Mensah later defected from the New Patriotic Party (NPP) to the National Democratic Congress (NDC), then in opposition.

[citation needed] Nunoo-Mensah was very instrumental in the campaign of the opposition NDC in the December 2008 elections in Ghana.