Engagement in organized physical activities offers numerous benefits for autistic people, yet persistent barriers hinder participation, especially as individuals age. This Australian study employed a mixed methods approach to investigate the experiences of organized physical activities among 103 autistic adults and 169 parents of autistic children. Although most autistic children were involved in such activities, participation significantly declined among autistic adults, with both groups expressing a desire for increased involvement. This research identified barriers spanning intrapersonal (anxiety, physical challenges), interpersonal (social communication difficulties), and societal (limited inclusive opportunities, insufficient autism awareness) domains. Key facilitators to enhanced participation included sensory accommodations, inclusive policies, improved accessibility, personalized coaching, and enhanced autism education for staff. These findings are consistent with international research and hold particular relevance within the Australian cultural context. This study represents a significant empirical contribution, shedding light on the intricate barriers and potential support mechanisms necessary to bridge the gap between the aspirations for organized physical activity and actual participation among autistic individuals throughout their lives. Realizing progress demands comprehensive changes across various levels, encompassing policies, programs, attitudes, and accessibility. Such transformations are essential to cultivate inclusive sporting cultures and counteract the disengagement observed from childhood through adulthood. Lay abstract Sports and physical activities can be really beneficial for autistic people, but they often encounter challenges, especially as they get older. In our Australian study, we surveyed 103 autistic adults and 169 parents of autistic children to better understand these challenges. We discovered that many autistic children take part in sports and activities, but as they become adults, it becomes harder for them to stay involved. Both the adults and parents expressed a desire for more opportunities for autistic individuals to participate. We also identified some common problems that make it difficult for autistic people to engage in these activities. These challenges include personal issues like anxiety and physical difficulties, difficulties with social communication, and broader societal issues such as a lack of inclusive opportunities and insufficient awareness about autism. On a positive note, we found effective strategies to make participation easier for autistic individuals. These include creating sensory-friendly environments, implementing inclusive rules, ensuring that places are easy to access, offering personalized support, and educating staff about autism. Importantly, our findings are not unique to Australia; they align with research from other countries. This study sheds light on the obstacles autistic people face in sports and activities and provides solutions to improve their experiences. To bring about meaningful change, we must adjust policies, programs, attitudes, and overall accessibility. This will foster inclusive sports and activities for autistic individuals from childhood through adulthood.