Onoja started his legal career with the firm Humphrey Adah & Co. in Lagos, from 1992 to 1996. He was on his own as principal solicitor at Onoja Consulting Solicitors before proceeding to the
University of Lagos for his
Master of Laws (LLM) degree between 1996 and 1997. From 1997 to 2000, he was with T.J. Onomigbo Okpokpo & Co., ad senior counsel. In 2000, Chief Onoja started another law firm, O.J. Onoja & Associates (incorporating Onoja Consulting Solicitors), and as principal solicitor, he represented individuals and corporate organisations in Nigeria in all levels of courts of record, arbitrary panels and other out-of-court negotiations. Onoja has attended several legal and academic conferences and workshops in Nigeria and abroad. He is a non-executive director of the following companies: Goomeej Nigeria Limited, Laser Guards Limited, Lugard Insurance Brokers Limited, Lugard Beach Hotels Limited, Lugard Realtors and Investment Limited, Lugard International School Limited, Lugardgate Ltd., Forte Lugard Ltd., Lugard Garrison Engineering Ltd., Bar and Bench Publishers Ltd, amongst others. Onoja is a member of the Nigerian Institute of Management, Fellow of the Nigerian Chartered Institute of Arbitrators, Fellow of the Nigerian Institute of Chartered Arbitrators, Member of the Nigeria Bar Association, Abuja and Lokoja, Fellow of Certified Cost Management, Fellow of Institute of Directors Nigeria and UK, and Member of Capital Market Consultants with Security and Exchange Commission. Onoja was appointed a Notary Public of Nigeria in 2008, while on 12 July 2012, he was elevated to the prestigious rank of Senior Advocate of Nigeria (SAN) on the platform of litigation and appearances at all level of courts in Nigeria. In recognition of his contribution to the development of the legal profession, the Honourable Chief Justice of Nigeria, W.S.N. Onnoghen, appointed Onoja as a member of the Legal Practitioners Privileges Committee, the body responsible for the appointment and discipline of Senior Advocates of Nigeria. He is currently the President of the Bar and Bench International Institute for Arbitration, an institute established for the resolution of disputes and the practice of alternative dispute Resolution. BBIIA provides education and training for arbitrators, mediators and adjudicators. It also acts as a global hub for practitioners, policy makers, academics and those in business, supporting the global promotion, facilitation and development of all ADR methods. BBIIA offers a range of resources including guidance, support, advice, networking and promotional opportunities, as well as facilities for hearings, meetings and other events. == Book authorship ==