The legal instrument establishing the Board was promulgated by the Act (No. 2 of 1978) of the Federal Military Government on 13th February, 1978. By August 1988, the Federal Executive Council amended Decree No. 2 of 1978.
The amendments have since been codified into Decree No. 33 of 1989, which took effect from 7th December, 1989. Decree No. 2 of 1978 (amended by Decree No. 33 of 1989) empowered the Joint Admissions and Matriculation Board to: (a) conduct Matriculation Examination for entry into all Universities, Polytechnics and Colleges of Education (by whatever name called) in Nigeria.