The parents of adolescents with autism spectrum disorder have a vital and proactive role in encouraging healthy physical activity habits, and they possess important knowledge about the adolescents’ needs when it comes to enhancing participation in physical activity. But promoting healthy physical activity habits in adolescents can be difficult. The purpose of this study was thus to describe parents’ perceptions of their adolescent child’s participation in physical activity and to describe the parental role in promoting such participation. Twenty-eight parents of adolescents aged 12–16 years with autism spectrum disorder were interviewed. The interviews were analyzed using an inductive content analysis approach. The parents described how challenging participation in physical activities could be for their adolescents. Despite this, they wanted to see their children participate more in physical activity but found the promotion of physical activity to be an overwhelming task that was difficult to cope with on their own. The results reveal a need for support and collaborative efforts among different actors to give these issues increased priority in order to promote the adolescents’ physical activity participation.