Sexual violence is one of the forms of violence against children worldwide. Understanding its magnitude and its associated factors is essential to promote effective protection policies to childhood. The objective was to verify the prevalence and analyze the factors associated with sexual violence against children in a Brazilian state. This is a cross-sectional study analyzing data from reported cases of violence against children in the state of Espírito Santo, Brazil, between 2011 and 2018. The characteristics of the victim, perpetrator and aggression were studied, and the associations were analyzed using Poisson regression. The frequency of sexual violence was 41.8% and was more prevalent in girls, in the age groups 3 to 5 and 6 to 9 years old, in white ethnicity/color and in the urban area. The offenders were mainly men, known to the victim and occurred mainly in the residence. Sexual violence was the most reported violence among children in Espírito Santo, occurring within their circle of trust, demonstrating the need to provide support for families and to advance public policies to guarantee children’s rights.