COVID-19 disease remains a public health emergency of international concern. Efforts at the global and national levels are being made to control its spread. The Nigerian Correctional Service is also proactive in the fight against the disease by organizing COVID-19 awareness training for correctional officers. We conducted a pre- and post-test assessment of COVID-19 knowledge among correctional officers in Enugu State Command to determine the impact of awareness training on their knowledge level. The study also assessed correctional officers’ attitude and preventive practices towards the disease. The mean knowledge score was 19.34 out of 25, and the awareness training significantly improved the participants’ COVID-19 knowledge. We found a significant moderate, positive correlation between knowledge and attitude/practice, and a significantly higher knowledge level among those with higher educational qualifications. The majority of the respondents (87.9%) believed that there were confirmed cases of COVID-19 in Nigeria, whereas 85.1%, 78.7%, and 75.9% believed that there were cases in other parts of the world, the world will win the battle against COVID-19, and that there will be successful control of the disease, respectively. Regular hand washing with soap and water was practiced by 87.9% of the participants, whereas 84.4%, 83%, and 58.9%, wore face masks in public places, practiced social distancing, and avoided crowded places, respectively. Obtaining information from multiple sources was the commonest (53.2%), and this was followed by the Nigeria Center for Disease Control (26.2%).