An estimated 1.7 million people were living with HIV in Nigeria in 2020, with over 86,000 people newly infected. Although the global rates of HIV have remained consistent over time, Nigeria has the second-highest number of people living with HIV and contributes to 9% of the global burden of HIV/AIDS. This is due to several structural and individual-level factors that limit knowledge of HIV and condom utilization. In this context, this study examines the association between knowledge about HIV transmission and consistent condom use among sexually active men in Nigeria. The data utilised in this study was sourced from the latest Nigeria Demographic and Health Survey conducted in 2018. The sample included a total of 9,346 men between the ages of 15–59 years who were sexually active at the time of data collection. Frequency distribution, univariate and multivariable analyses were performed at 95% confidence interval and p-value less than 0.05 to determine the association between the key independent variables and covariates. The results showed that 85.03% of sexually active men who had no knowledge of HIV engaged in inconsistent condom use. The key independent variable showed that sexually active men who had knowledge of HIV had higher odds [AOR = 1.37; 95%(CI = 1.10–1.72)] of consistent condom use compared to those without knowledge of HIV. However, sexually active men who were previously married [AOR = 0.38; 95%(CI = 0.24–0.61)], and those residing in the South Eastern region of Nigeria [AOR = 0.62; 95%(CI = 0.44–0.96)] had lower odds of consistent condom use. This study established the association between HIV knowledge and consistent condom use among sexually active males in Nigeria even after controlling for confounders. Educational level, wealth index, and ethnicity are also associated with condom use. This calls for the consideration of social determinants of health, localised and cultural health promotion and targeted public health strategies at all governmental levels to combat the HIV/AIDS epidemic in Nigeria.