‘The Upheaval in Nigeria Oil Marginal Field Law: A Comparative review of Nigerian Petroleum Act 1969/1990 with that of UK, USA and Canada (With Relevant Updates from the Nigerian Petroleum Industry Act 2021)’ is a review of the Nigerian Petroleum Act with the Petroleum laws of UK, USA and Canada to clarify the legal position of Nigeria oil marginal field farm-out exercise that raised international concern, for improvement to enable international best practice. This research traced the authority behind natural resources development and foreign direct investment, through the resolutions and policy statements of the United Nations and the Organisation of Petroleum Exporting Countries. It also discussed petroleum business arrangements and Nigeria oil marginal field regulations in existence for proper understanding, with a review of Nigeria marginal field development prospects and technologies, policy rationale, barriers, and effects. It resolved that the legality of the government farm-out exercise was drawn from the combined provisions of the United Nations resolutions on the rights of developing countries to enjoy permanent sovereignty of their natural resources and the declaratory statements of the Organization of Petroleum Exporting Countries, on the necessity of member countries to make policy development to take charge of their natural resources. This authority was incorporated under the Nigerian law by the combined provisions of Section 44(3) of the Constitution of the Federal Republic of Nigeria and Section 17(1)-(4) of the First Schedule (Amendment Decree No.23 of 1996) of the Nigeria Petroleum Act 1969/1990. In essence, this research introduces a unique contribution to knowledge, as it demonstrated that the Nigeria government farm-out exercise that raised international concern was fair, justified, and legal but requires a cautionary application to avoid driving away investors. It also demonstrated that it is a sensible practice to develop oil marginal fields alongside renewable energy as a backup support, to aid the development and gradual switch to renewable energy.