Background: Currently, 6.3 million people have been infected with severe acute respiratory syndrome (SARS)—CoV-2 and the pandemic has spread to 216 countries. To date of 6th June 2020, 383,262 deaths were confirmed. Objective: We aimed to evaluate the knowledge, attitudes, and practices (KAP) toward COVID-19 among the population. Materials and methods: This cross-sectional study was conducted in 614 residents of Ulaanbaatar city by online survey. The Ethics Committee of Institute of Medical Sciences, Mongolian National University of Medical Sciences, Mongolia, approved our study protocol, procedures, information sheet, and consent statement (№2020/D-11). The questionnaire consists of 45 questions, including general information, KAP. The KAP were evaluated by 20, 14, and 9 scores, respectively. Results: The mean scores of participants were determined and ranked into levels of good, average, and poor. Appropriate statistical methods were performed. The mean age of participants were 32.14 ± 10.82 (12–86) years and 70% were women. The mean score of knowledge questionnaire was 13.73 ± 2.7 (13.7 ± 2.3 in male, 13.8 ± 2.6 in female, p = 0.221) which refers that 72.5% (445) of participants had a mean score of knowledge. Furthermore, the mean score of attitude was 13.2 ± 2.7 (13.7 ± 2.3 in male, 13.8 ± 2.6 in female, p = 0.221) and the mean score of practice was 6.9 ± 1.6 (6.3 ± 1.7 in male, 7.1 ± 1.6 in female). Conclusion: The population has a relatively good level of KAP toward COVID-19.