To assess the effectiveness of modified constraint-induced movement therapy (mCIMT) in improving upper limb function and grip strength in children with hemiplegic cerebral palsy (CP).A comprehensive search was conducted from inception to August 2024. Eligibility criteria were studies evaluating the effectiveness of mCIMT on upper limb function in children with hemiplegic CP aged over 2 years. The following data was extracted from each study: participant characteristics, intervention, outcome measures, follow-up, and key findings. The risk of bias and the quality of the evidence were evaluated using the PEDro scale and the grading of recommendations assessment development and evaluation (GRADE), respectively. A meta-analysis using a random-effect model was performed, and standardized mean difference (SMD) with a 95% confidence interval (CI) was estimated for upper limb function and grip strength.A total of 25 studies (1,115 children) were included. PEDro scale revealed 12 good-quality studies, 8 fair-quality studies, and 5 poor-quality studies. The currently available evidence showed a significant large effect of mCIMT in improving upper limb function (SMD: 1.14 [95% CI: 0.46-1.83]; p = 0.001; 12 studies; 454 children; very-low-quality evidence) and significant medium effect in improving grip strength (SMD: 0.63 [95% CI: 0.12-1.14]; p = 0.02; 3 studies; 92 children; low-quality evidence).mCIMT could improve upper limb function and grip strength in children with hemiplegic CP. However, due to the low and very low quality of evidence, further high-quality trials are needed to confirm these effects.PROSPERO registration number (CRD42023413525).