Abstract: The study investigated undergraduate’s awareness, utilization and satisfaction with Online Public Access Catalogue (OPAC) in selected University libraries in Nasarawa State, Nigeria. About 4 objectives with corresponding research questions guided the study. The study adopted survey research design. The population of the study was 7,233 registered library users (undergraduates) in (2) public universities in Nasarawa State, namely Federal University Lafia (FULAFIA) and Nasarawa State University, Keffi (NSUK). The sample size for the study was 379 drawn using Taro-Yemene’s formula for sample size determination. Proportionate stratified random sampling technique was used to select the sample of respondents from the (2) universities under study, i.e., FULAFIA with 150 and NSUK, 299, respectively. Questionnaire was used as instrument for data collection. A total of 379 questionnaire were distributed and 362 retrieved for analysis representing a percentage of 95.5%. Data was analyzed using frequency counts; mean scores and standard deviation. Findings of the study revealed that, undergraduates were highly aware of Online Public Access Catalogue in selected University Libraries in Nasarawa state. The finding also revealed, undergraduates in selected university libraries in Nasarawa state utilized OPAC to a little extent and students were not satisfied with the use of OPAC, hence their extent of satisfaction derived from the use of OPAC was little extent. Findings further revealed factors affecting use of OPAC by undergraduates in selected university libraries to include library guide to explain how to use the OPAC is not available, unstable power supply, library staff not friendly, network/server problems, lack of computer systems, among others. Finally, conclusion and recommendations were made based on the findings of the study.