BACKGROUND: Brazil is facing increasing cycles of numbers of infected people and deaths resulting from coronavirus disease 2019 . This situation involves a series of factors, including the behavior of the population, that can be decisive for controlling the disease. OBJECTIVE: To determine the knowledge, attitudes and practices of the Brazilian population regarding COVID-19. DESIGN AND SETTING: Cross-sectional survey-type study, conducted using a population sample from different Brazilian states. METHODS: A quantitative, descriptive and analytical approach was used. Sampling was done according to convenience and via snowballing. The data collection instrument was a knowledge, attitudes and practices system. RESULTS: 1,655 people from all over Brazil participated in the survey; 80% were living in the southern region and 70.15% were female. More than 90% had knowledge and good attitudes relating to the means of transmission, preventive care and symptoms associated with COVID-19, although their knowledge and attitudes were not fully reflected in daily practices, for which there was lower adherence (80%). Greater knowledge was correlated with older participants, larger number of children, female sex and marital status; better attitude, with female sex and complete higher education; and better practices, with greater age, larger number of children and female sex. CONCLUSION: A large part of the population has general knowledge about COVID-19, but not all knowledge was applied in practice. Older people, females and university graduates stood out as the best informed and most committed to controlling the disease.