Access to justice in criminal matters is a fundamental requirement for the protection of human rights, the promotion of the rule of law, and the realization of sustainable development. However, poor and indigent persons in Nigeria continue to face significant barriers in accessing justice due to poverty, weak institutions, prolonged pre-trial detention, inadequate legal representation, delays in criminal trials, and ineffective coordination within the criminal justice system. This article examines the concept of justice and access to justice for the poor in criminal matters and analyses the international, regional, and national legal frameworks regulating legal aid and criminal justice administration in Nigeria. Particular attention is given to the provisions of the Constitution of the Federal Republic of Nigeria, the Administration of Criminal Justice Act 2015, the Legal Aid Act 2011, and the National Legal Aid Strategy. Using doctrinal and empirical research methods, the study evaluates the role of the Nigerian Legal Aid Council and institutional law clinics, particularly the Yenagoa and Bagauda Law Clinics, in promoting access to justice through legal representation, legal literacy programmes, prison outreach, legal counselling, and advocacy initiatives.