This project aimed at assessing the application and impact of forensic science in the Nigerian criminal justice system by making reference to certain components of forensics that are relevant to the criminal justice system. Such components include Deoxyribonucleic Acid (DNA) analysis, Fingerprint analysis, Polygraph test, Ballistics, Forensic anthropology, Forensic pathology and Computer forensics. The justification for this research arose out of the alarming rate crimes are constantly committed and the apparent difficulty faced by agencies of the criminal justice system while trying to curb the occurrence of such crimes. The sources of information relied upon here are relevant books, articles in journal publications, internet materials, statutes and judicial authorities. In the course of this research, it was found that establishing certain types of evidence such as fingerprint impressions and DNA, against accused persons was seriously hindered due to the absence of forensic labs and this hinder the conviction of such persons. In view of this, this research recommended inter alia, for proper training of law enforcement agencies in terms of how crimes and crime scenes are handled and also the establishment of sophisticated forensic labs where evidence and accused persons can be taken to in order to determine guilt or innocence in order to ease the establishment of evidence before law enforcement agencies in Nigeria.