Within a short period of time, COVID-19 has spread globally, wreaking havoc in various facets of life. This study sought to measure the level of COVID-19 knowledge, attitudes, and practices of the Nigerian public. This was a cross-sectional online survey of the general population of educated Nigerians who had Internet access. Sociodemographic data and participants' knowledge, attitudes, and practices relating to COVID-19 were collected. Scores assessing knowledge, attitudes, and practices were allocated and graded based on specific stratified demarcations. Student's t-test, analysis of variance, and logistic regression analysis were used where appropriate. Of the total 1,015 respondents, most of them exhibited good knowledge of COVID-19, with a mean knowledge grade of 78%; this significantly affected their attitude and practice grades (66% and 60.4%, respectively). Most respondents expressed positive attitudes toward foreigners and other stigma-prone groups, while also practicing appropriate preventive measures. Those aged 21-30 years and those with medical-related occupations had significantly higher knowledge scores (P < 0.001); and having a medical-related occupation increased the likelihood of having good knowledge compared with being unemployed (odds ratio [95% CI]: 6.6 [2.5-17.3]). Male participants aged 21-30 years and those with medical-related occupations had significantly higher attitude scores (P < 0.05). Engaging literate Nigerians on various media platforms, particularly social media, will result in wider reach for the purpose of COVID-19 education. Further studies on other sociodemographic groups within the country (e.g., the less educated) would give a clearer picture of the Nigerian situation as regards COVID-19 knowledge, attitudes, and practices (coronavirus, COVID-19, Public health, Nigeria, Africa).