AimTo investigate the efficacy and safety of high-calorie formula vs. Chinese daily food on the nutritional status and motor function of undernourished children with cerebral palsy (CP).MethodsIn this prospective, assessor-blind, and randomized controlled trial, we recruited children (1–10 years) with CP and undernutrition based on the WHO and the American Society for Parenteral and Enteral Nutrition criteria from the National Children's Medical Center. Participants were randomly allocated (1:1) to a high-calorie formula group or a Chinese daily food diet group (control group) for 6 months. Indirect calorimetry was used to estimate energy requirements. We compared the nutritional status and gross motor function of participants in both groups based on weight, height, z-scores (weight-for-age, height-for-age, weight-for-height, and BMI-for-age), and the Gross Motor Function Measure (GMFM), respectively, at baseline, 3-, and 6-months follow-up. In addition, the effective rate of nutritional intervention, and adverse events were simultaneously assessed.ResultsFrom July 2020 to December 2021, a total of 119 participants were enrolled and randomized, and 110 participants completed the study (with 54 children in the high-calorie formula group and 56 children in the control group). After 6 months of treatment, the weight, height, z-scores (weight-for-height, weight-for-age, and BMI-for-age), and GMFM of both groups were significantly improved (p < 0.05). There were significant differences in changes in weight, weight-for-age z-scores, and GMFM between the two groups (p < 0.05). During the study period, 16 children experienced at least one mild adverse event [9 (16.7%) in the formula group and 7 (12.5%) in the control group].ConclusionNutritional intervention with a high-calorie formula may be an effective and safe option in children with CP for improving undernutrition and gross motor dysfunction.Clinical trial registrationwww.chictr.org.cn, identifier: ChiCTR2000033878.