Adewale was born in Ode Remo in present-day Ogun State in southwestern Nigeria.
He was one of the first graduates that enrolled as an officer in the Nigerian Army along with Lieutenant Colonels Chukwuemeka Odumegwu-Ojukwu and Victor Banjo, and Majors Olufemi Olutoye, Emmanuel Ifeajuna, and Oluwole Rotimi in the 1966 Nigerian army.
Major Ademoyega was released from detention by Biafran Head of State Colonel Chukwuemeka Odumegwu-Ojukwu, on August 13, 1966.
He then formed the Biafran 19th Battalion and subsequently took over for Major Emmanuel Ifeajuna, who also helped with the 1966 coup as the chief of staff of the Liberation Army.
However, Federal forces put him right back in detention for his participation as part of the Liberation Army.