Dr. Onah was born on 4th April, 1965 at Aneka-Owo, Oju Local Government Area of Benue State.
He started his educational pursuits at the LGEA School, Ameka-Owo, Oju local government in1972from where he obtained his FSLC in 1977. He was to later proceed to Mt. St. Michael’s Secondary School, Aliade where he studied between 1977 and 1982, passing out with GCE “O” Level. That same year, he got admitted to the University of Jos, Plateau State to study medicine, and graduated in 1988. After his compulsory youth service year as Director of the Health Centre in Isi-Uzo local government in Enugu State, he returned to Jos for an M.Sc. in Anatomy, which he obtained in 2011. He is currently undergoing a Ph.D programme in Anatomy at the same university.
His working career spans several years and in different places within the country. He was a Medical Officer with Chinemelu Hospital Obollo-Affor, Enugu State, and later served as Medical Director, Holycross Hospital, Oju, Benue State, as well as Medical Superintendent in-charge of General Hospital, Nasarawa, Keffi, Nasarawa State. He was also a lecturer in the Department of Anatomy, College of Health Sciences, Benue State University.
In the last Assembly, he was, at various times, Chairman of the committee on public petitions, bills review and appraisals,member, House Committee on Education, as well as member, House Committee on Women Affairs.
Hon. Dr. Onah, has received several awards from corporate organizations in the course of his distinguished public service career, including Fellow of Civilian Institute of Democratic Administration (F-CIDA), Ghana, as well as an award of Excellence by the Nigeria Medical Association (NMA) Benue State chapter.
He is a member of the Nigeria Medical Association: member, Anatomical Society West Africa and member of Neuroscience Society of Nigeria, among several others.
He is married with children.