Environmental justice (EJ) is a progressively advancing subject, social movement and practice, which requires fair treatment and meaningful involvement of all humans, regardless of sex, age, class, income, race, colour or nationality, in the development, management, implementation and enforcement of plans, policies, laws and regulatory practices, towards the protection and management of the environment in the course of socio-economic development programmes, including projects. It also requires equitable and thus indiscriminate exposure of all to environmental good and harm. It is an advancing social movement that advocates a healthy and eco-balanced environment, towards human wellbeing, sustainable communities and all-embracing sustainable development (SD) in the overall interest of society within our Planet (Mother Earth). EJ may thus be discussed within the rubrics of the twin relationship of the environment to development, in the ongoing effort of the UN to achieve SD around the world. Hence, this socio-legal study examines efforts of EJ Nongovernmental Organisations in the oil-rich ethnic minority Niger Delta region, towards greater wellbeing of the environment, humans and society at large in the region and beyond. The study makes a case for application of international benchmarked norms, guidelines, standards and practices on EJ beyond advanced countries, particularly to underprivileged areas of the developing world, such as the marginalized and neglected oil-rich ethnic minority communities of the Niger Delta region and other such deprived resource-rich areas of other developing countries.