This study evaluated the regulation of deepfake technology in Nigeria, with particular emphasis on the criminal law challenges associated with artificial intelligence-generated synthetic media and approaches for legal reform. The study explored the development and applications of deepfake technology such as its beneficial uses in entertainment, education, healthcare and communication, while focusing on its misuse in fraud, identity impersonation, non-consensual sexual content, misinformation and manipulation of digital evidence. The research adopted doctrinal methodology which involved the analysis of Nigerian criminal law frameworks, relevant judicial decisions, statutory provisions and comparative regulatory approaches from the European Union, United States, China and United Kingdom. The study finds that existing Nigerian legal instruments; the Criminal Code Act, Penal Code Act and Cybercrimes (Prohibition, Prevention, etc.) Act 2015, provide limited legal responses to some deepfake-related harms but fail to expressly regulate the creation, distribution and malicious use of synthetic media. The findings revealed significant challenges relating to criminal attribution, proof of intent, and authentication of AI-generated evidence, anonymous online actors and cross-border enforcement. Comparative analysis showed that effective deepfake regulation requires specific criminal offences, transparency obligations, technology provider responsibilities, and reliable evidence verification mechanisms and enhanced digital forensic capacity. The study recommended the enactment of deepfake-specific legislation, amendment of existing cybercrime laws and strengthening of institutional capacity for investigation and enforcement.