Purpose: To investigate the effectiveness of a practitioner-led, peer-group sports intervention for children with CP at GMFCS Level I-II. Method: Children with CP (GMFCS I-II; 6-12 years) were randomised to Sports Stars or waitlist-control groups. Sports Stars included eight-weeks (eight hours) of physiotherapist-led, sports-specific gross motor activity training, sports education, teamwork development and confidence building. Sports participation was measured using self-identified participation goals (modified Canadian Occupational Performance Measure (mCOPM)). Physical competence was measured with mCOPM activity goals and high-level gross motor batteries (Test of Gross Motor Development (TGMD-2); GMFM-Challenge) and walking (Timed-Up-and-Go), running (Muscle Power Sprint Test; 10x5m Sprint Test), jumping (Standing Broad Jump; Vertical Jump) and throwing (Seated Throw) items. General participation and quality of life were also measured. Outcomes were measured pre, post and 12-weeks post-intervention. Data were analysed using linear mixed models. Results: Fifty-four children were randomised into Sports Stars ( n = 29; GMFCS I = 7, II = 22; male = 19; 8.9 ± 2 years) or waitlist-control groups ( n = 25; GMFCS I = 10, II = 15; male = 14; 8.6 ± 2 years). The Sports Stars group improved sports participation and activity goals (mCOPM F = 5.49-10.29, p < 0.001) and sports-specific physical competence (TGMD-2, F = 3.45-5.19, p = 0.001-0.009) compared to the waitlist-control. Conclusion: Sports Stars is effective for improving sports-specific participation and physical competence for children with CP.Implications for rehabilitation Sports Stars improves performance and satisfaction in sports-specific participation and activity goals for ambulant children with CP. Sports Stars improves sports-specific physical activity competence in locomotor and object control skills.Sport-specific interventions should incorporate sport-specific gross motor activity training as well as sports education, confidence building and teamwork.