This study applies an intervention based on autonomy support through dialogic learning to examine effects on motivation and the promotion of physical activity and sport involvement during schoolchildren’s leisure time. One hundred and two primary school students, aged 11–13 years, participated (M = 10.93, SD = 0.75). The sample was divided into two groups: an experimental group (49 students) and a control group (53 students). A quasi‐experimental study was conducted in physical education classes over the course of 9 months. Assessments of autonomy support from teachers, family, and peers; basic psychological needs; self‐determined motivation in physical education and during leisure time; planned behavior variables; physical activity intention; and estimated and actual physical exercise behavior time were included in the model. Following the intervention, the results revealed that greater autonomy support by the teacher, the family and peers, satisfaction of the basic psychological needs, self‐determined motivation during physical education class and during free time, greater perceived control, favorable attitude and intention to engage in physical activity contributed to the explanation of student physical activity involvement. These results suggest that when students receive extensive social support from diverse social agents that essential precursors to physical activity are strengthened and contribute to increased motivation and actual physical activity involvement. Efforts to promote effective communications with students and other pedagogical efforts, such as providing dialogic learning opportunities, should be considered in order to strengthen physical activity motivation and involvement in students.