The current study aimed to explore the association of individual characteristics, social and environmental factors - school and region - in the intention to be physically active in Brazilian adolescents. This is a cross sectional study based on the third edition of the National School Health Survey. The study included a total of 53,937 adolescents. To assess the intention to be physically active, only who engaged in less than 300 min of physical activity per week were included. Participants were asked: "If you had the opportunity to practice physical activity most days of the week, what would your attitude be?" Individual characteristics, physical activity domains, social factors, school, and regional environments were used as exposures. Network analysis was utilized to evaluate the associations. We observed that boys had higher intentions to be physically active compared to their peers, as did adolescents who perceived themselves as fat. In addition, students from private schools show a higher intention to regularly engage in physical activities, and in general, private schools offer more extracurricular physical activities. In conclusion, individual factors such as sex and body image perception, and environmental factors such as school administrative dependency and availability of extracurricular activities had a significant contribution to the intention to be physically active among Brazilian adolescents.