Samuel Onunaka Mbakwe was born in 1929. He began his education in 1937 at St Peter's primary school, Umulogho. He studied at the Teachers Training College, Oleh, Isoko, from 1946 to 1947, and at Fourah Bay College, Sierra Leone in 1952. He moved on to the University of Manchester and was there from 1953 – 1956. He also schooled the University of Hull from 1956 –1958, and the Inns of Court from 1958–1959 in England, before returning to Nigeria to practice law in Port Harcourt, Eastern Region.k Mbakwe served as an Administrator of Okigwe Province in the Republic of Biafra, an Igbo secessionist state in southeastern Nigeria, during the 1967–70 Civil War.
Mbakwe joined the Constituent Assembly in 1978 and became governor on October of the following year 1979. One of the main priorities of his administration was to improve Imo State's roads. He was re-elected, but his second term was interrupted by General Muhammadu Buhari's military coup of 31 December 1983, which brought about the end of the Second Republic.
Sam earned the nickname "the weeping governor" for crying while trying to convince the federal government to pay more attention to his state; the first occasion of his tears was the Ndiegoro flood in Aba, which was then a part of Imo State. He had invited President Shehu Shagari to witness the destruction done by the floods, and he was moved to tears while showing the president the disaster area.
One of his quotes is in 1995 says, "If you have not been in prison before, that will be your baptism and qualification. You will learn from the prison yard that not all those in detention are criminals."
The Sam Mbakwe International Cargo Airport, which is located in Owerri, the state capital,is named after him. In 1981, he set up Imo State University. The school was located in a territory that was given to Abia State in 1991 and was re-christened Abia State University. Imo State University acquired a new campus in Owerri and it still exists.
His 6 January 2004 death in Avutu, Obowo Local Government Area, came after a sickness that had set on in February 2002 and occurred shortly after a state-sponsored trip to Germany for treatment.
He died on the 5th of January 2004.