Background <p>This systematic review and meta-analysis aimed to evaluate the effects of environmental enrichment (EE) in infants with or at high risk of cerebral palsy (CP), as well as to identify the most effective age window for intervention.</p> Methods <p>PubMed, Embase, the Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature, the Web of Science Core Collection, Psychological Information Database, and Sociological Index were searched from database inception to 27 February 2025. All data analysis was performed using Stata 17.0. Differences were expressed using standard mean difference (SMD) with 95% confidence interval (CI). Outcomes, including motor development, gross motor function, fine motor function, and cognitive development, were investigated.</p> Results <p>Fourteen randomized controlled trials with 592 participants were included. Of the 14 included articles, 50% were assessed as low risk, 36% were assessed as some concerns, and 14% were assessed as high risk. EE interventions significantly improved motor development (SMD = 0.35; 95% CI = 0.11 to 0.60; <i>p</i> = 0.004), gross motor function (SMD = 0.25; 95% CI = 0.06 to 0.44; <i>p</i> = 0.011), and cognitive development (SMD = 0.32; 95% CI = 0.10 to 0.54; <i>p</i> = 0.004) in infants with or at high risk of CP. No significant effect was observed on fine motor function. Subgroup analyses indicated that the optimal age window for EE is 6-18 months for motor development and 6-12 months for cognitive development. The overall quality of evidence ranged from high to low.</p> Conclusions <p>EE interventions significantly improve motor development, gross motor function, and cognitive development in infants with or at high risk of CP.</p> Trial registration <p>The protocol of this study was registered in PROSPERO (CRD42024523400).</p>