In his years of active service, Gambo Jimeta attended Detective Training School, Wakefield, United Kingdom, in 1962; Bramhill Police College, United Kingdom, in 1963; International Police Academy, Washington DC, USA, in 1980; and the National Police Academy, Cairo, Egypt. In 1982, he was promoted to the rank of Assistant Inspector General of Police (AIG) and transferred to the Force Criminal Investigation Division, Alagbon Close, Lagos. After the military took over government in December, 1983, when it overthrew the Second Republic, Gambo Jimeta was appointed the Deputy Inspector General of Police (DIG) to the then IGP Etim Inyang in January, 1984. At that time, only one DIG was appointed for the IGP. In 1986, he was appointed to succeed his boss, Etim Inyang, as Nigeria’s seventh Inspector General of Police and served until 1990 when he was succeeded in the same capacity by Aliyu Attah. He thereafter served as the National Security Adviser (NSA) to Nigeria’s former Military President, General Ibrahim Badamasi Babangida. In 2011, former President Goodluck Jonathan appointed Gambo Jimeta as a member of the Presidential Advisory Committee on Prerogative of Mercy.