This study examined the relationship between cybersecurity measures and operational efficiency in the Eastern Nigeria seaports. The study adopted an explanatory research design; and surveyed one hundred and twenty respondents of 4 seaports in Eastern Nigeria. However, 114 copies were considered fit for the study. The Pearson Product Moment correlation was used to analyze data retrieved from respondents. The results indicate that cybersecurity measures have a very strong positive and significant relationship with the measures of operational efficiency (cargo dwell time, ship turnaround time and cargo throughput) in the Eastern Nigeria seaports. Therefore, we concluded that the seaports in Eastern Nigeria should adopt cybersecurity measures in order to maintain operational efficiency in the long run. It was recommended that ports managers and stakeholders should implement comprehensive cyber defense strategies, including regular vulnerability assessments, data encryption, and real-time monitoring of networks in order to achieve operational efficiency in terms of cargo dwell time, ship turnaround time and cargo throughout.