<p> Objective Controversies consistently accompanied the development of surgical treatment strategies for Chiari I malformation (CIM). This study aims to evaluate the reliability of the cerebellar tonsil remodeling procedure for CIM with syringomyelia and identify independent prognostic factors for excellent relief postoperatively in CIM. Methods We enrolled 48 patients for this study based on the inclusion and exclusion criteria. Patients were assigned to two groups based on the different surgical interventions: the extra-arachnoid decompression and cerebellar tonsil remodeling groups. We utilized the Chicago Chiari Outcome Score to quantify the symptom remission of patients after surgery. We compared the outcomes of the two groups and identified the prognostic indicators for the excellent postoperative relief. Results A significant difference was observed between the two groups regarding postoperative excellent relief (23.8% vs. 66.7%, <i>p</i> = 0.003) and syringomyelia remission (47.6% vs. 85.2%, <i>p</i> = 0.005). The increased volume of the cisterna magna (CM) (<i>p</i> = 0.011), the duration before diagnosis (<i>p</i> = 0.016), and the various surgical interventions (<i>p</i> = 0.014) were independent prognostic factors for postoperative excellent relief based on univariate and multivariate logistic regression analyses. Conclusion The cerebellar tonsil remodeling procedure is a reliable treatment for patients with CIM and syringomyelia. The procedure significantly increase the volume of the CM without introducing additional cerebrospinal fluid-related complications. Furthermore, early surgical intervention improves outcomes in patients with CIM with syringomyelia.</p>