BackgroundParticipation in organised and non‐organised physical activities among adolescents and young adults with Down syndrome is underexplored. This study aimed to examine differences between organised and non‐organised physical activities among adolescents and young adults with Down syndrome.MethodsForty participants with Down syndrome (27 woman; mean age 21.4 ± 4.9 years) were recruited. Data on physical activity participation were collected by self‐ or proxy‐reported questionnaires about attendance, involvement and type of physical activity.ResultsAdolescents and young adults with Down syndrome participated in more organised than non‐organised activities (P < 0.05), more often (P < 0.05), but there was no difference in the total time spent participating in these activities overall. Participants spent more time in vigorous physical activity during organised activities (P < 0.05) and spent more time in light physical activity during non‐organised physical activities (P < 0.05). Dancing (organised activity) and walking (non‐organised activity) were the most reported activities.ConclusionsParticipation in both organised and non‐organised physical activities is important to increase overall physical activity levels of adolescents and young adults with Down syndrome. Future research exploring physical activity preferences may help guide the planning and adaption of community programmes for this group.