Background: Most activities of daily living require more than one activity, including motor-motor or motor-cognitive task. Few studies have investigated the effects of dual-task training in children with cerebral palsy (CP). Aims: This study was aimed at investigating the effectiveness of motor-cognitive dual-task exercise training in children with cerebral palsy (CP). Methods: A single-blind randomized controlled trial was conducted with thirty children with CP. Participants were randomized into dual group training group (DTG) and control group (CG). Children were evaluated before the intervention and after 12 weeks of treatment with Gross Motor Function Classification Scale (GMFCS), Pediatric Berg Balance Test (PBBS), Single Leg Stance Test (SLST), Timed Up and Go Test (TUG), 3 Meter Backwards Walk Test (3-MBWT), 6 Meter Walk Test (6-MWT), and General Children’s Quality of Life Measure (KINDL). Results: DTG demonstrated significantly improved all KINDL scores (p < 0.01). In comparisons between groups adjusted analysis, results showed a better improvement of all KINDL scores in-favor-of DTG (p < 0.01). Significant improvements were found in all SLST scores and PBS in DTG (p < 0.01). Adjusted analysis results proved there was a significant improvement in all balance scores on behalf of DTG (p < 0.01). Significant improvement was observed in DTG for TUG, 3MBWT, and 6MWT scores (p = 0.001). An improvement in-favor-of DTG was found for all performance tests in the adjusted analysis (p < 0.001). Conclusion: The results of this randomized controlled trial highlighted the advantage of dual-task training on balance, physical performance, and quality of life in children with CP.