In Essentials of Criminal Law in Nigeria, the author examines fundamental concepts and principles underlying Nigerian Criminal Law. Part I, which consists of six chapters, covers a general introduction to criminal law in Nigeria, principles of criminalization, the history of criminal law, principles of criminal liability, legal elements of a crime, content and types of criminal responsibility, general defences to criminal responsibility, preliminary or inchoate offences, and the criminal liability of parties to offences. Part II of the book consists of chapters seven to thirteen and covers non-sexual personal offences, sexual personal offences, non-violent property offences, the defence of bonafide claim of right, violent property offences, offences against the State, offences relating to the administration of justice and miscellaneous offences such as forgery, uttering, corruption and money laundering. The analysis of the essential concepts and principles of Nigerian Criminal law is enriched with a clear and in-depth analysis of the provisions of the Criminal Code, Penal Code, the Criminal Law of Lagos State and other relevant federal criminal legislation including the Economic and Financial Crimes Commissions (Establishment) Act, the Advance Fee Fraud and Other Related Offences Act and the Money Laundering (Prevention and Prohibition) Act 2022, among others. The author reviewed decisions of Nigerian courts, relevant decisions of English courts, Australian State of Queensland courts and some courts in East African Countries with Penal Laws containing similar provisions to the Criminal Code. Essentials of Criminal Law in Nigeria was designed primarily for undergraduate Law Students in Nigeria. It will however be a useful tool for judges, law lecturers, legal practitioners and others because of its systematic analysis of the concepts, principles and essentials of Nigerian Criminal Law.