The improvement of physical fitness parameters is beneficial for child gymnasts to maximize functionality. Core stability exercises (CSEs) help maintain spinal stabilization during athletic performance. Thus, they contribute to enhancing gymnasts' performance on various movements and planes. This study aimed to investigate the effect of 8-week CSEs training on the physical fitness parameters of child gymnasts. An 8-week CSEs intervention could be beneficial for improving the various physical parameters in child gymnasts. Randomized trial. Level 2. Thirty-six child gymnasts (aged 7-12 years) were allocated randomly into a training group (TG) and control group (CG). Participants in the TG received CSEs in addition to the traditional program for 8 weeks. The physical fitness parameters of all participants were assessed twice before and after training. The results showed that all participants' scores of balance, endurance, sprint, and jumping parameters improved after exercise programs (P < 0.05). The muscle strength and flexibility scores of the TG showed a statistically significant difference compared with the CG (P < 0.05). However, compared with other parameters, there were no significant changes seen in the scores between groups (P > 0.05). The CSEs training contributed to the improvement of all physical fitness parameters in child gymnasts. The addition of CSEs to traditional training could help improve athletic performance in child gymnasts.