Background: Children with cerebral palsy (CP) may have difficulties under dual-task conditions. Spatiotemporal gait parameters have deteriorated with concurrent tasks in children with CP. However, how dual-task training affects gait parameters in children with spastic diplegic CP has not been clarified. Research question: How does dual-task training program effect gait, functional skills, and health-related quality of life in children with spastic diplegic CP? Methods: Eleven children with spastic diplegic CP (median age 11 y, range 7–16 y; 4 female; 7 male) Gross Motor Function Classification System level 1–2 and obtained 27 and higher scores from Modified Mini Mental Test included in the study. The study was planned as a self-controlled clinical research design. Children were recruited to conventional physiotherapy program for 8 weeks and dual-task training program added to conventional physiotherapy program for following 8 weeks. Children were evaluated at baseline, after conventional physiotherapy program, and after dual-task training program. Children's gait was evaluated with Zebris™ FDM-2 device and Edinburgh Visual Gait Score, functional mobility skills with 1 min Walk Test (1MWT), and health-related quality of life with the Pediatric Quality of Life Inventory (PedsQL) - CP module. Results: The difference in step length, step time, stride time, cadence and gait speed of spatiotemporal parameters of gait during dual-task performance were found statistically significant in children with spastic diplegic CP, after dual-task training program (p < 0,05). After dual-task training, statistically significant gains were found in 1MWT, movement and balance subtitle of PedsQL-CP module Parent Form (p < 0,05). Significance: Dual-task training program added to a conventional physiotherapy program provides more gains in terms of functionality of children with spastic diplegic CP will contribute to the improvement of the motor functional level.