Inyang was born in EnwangMbo, Akwa Ibom, the son of Okon Inyang the traditional ruler at Enwang. He had his education at the Roman Catholic School, Uko-Akpan (1936 - 1937), Methodist School, Oron (1939 - 1940) and Oyubia Secondary School, Oron (1941 - 1945). Before he joined the police force, Inyang was a teacher between the years 1946 and 1949.
Inyang joined the Nigeria Police Force as a Constable in October 1949, he became a Lance Corporal in 1957 and was made Corporal in 1958. He became an Inspector in 1958, Assistant Superintendent of Police, (1960 - 1963), Deputy Superintendent of Police (1963 - 1965) and Superintendent of Police in 1965. He was Chief Superintendent of Police (1967 - 1971), Assistant Commissioner of Police (1971 - 1974), Commissioner of Police (1975 - 1980). Between 1961 and 1971, he was an officer at the INTERPOL office of the Central Criminal Investigation Department. In 1974, he managed the establishment of a Traffic Warden Service in the police force. Inyang was Assistant Inspector General of Police (1980 - 1984) and Inspector General in 1984.