Pelvic bone tumor resections remain significantly challenging due to complex three-dimensional anatomy and limited surgical visualization. While accurate, current navigation systems and patient-specific instruments present limitations, including high costs, radiation exposure, workflow disruption, long production time, and lack of reusability. This study evaluates a real-time vision-guided surgical system combined with modular jigs to improve accuracy in pelvic bone tumor resections. A vision-guided surgical system combined with modular cutting jigs and real-time optical tracking was developed and validated. Five male pelvis sawbones were used, with each hemipelvis randomly assigned to either the vision-guided and modular jig system or the traditional freehand method. A total of 20 resection planes were analyzed for each method. Accuracy was assessed by measuring distance and angular deviations from the planned resection planes. The vision-guided and modular jig system significantly improved resection accuracy compared to the freehand method, reducing the mean distance deviation from 2.07 ± 1.71 mm to 1.01 ± 0.78 mm (p = 0.0193). In particular, all specimens resected using the vision-guided system exhibited errors of less than 3 mm. Angular deviations also showed significant improvements with roll angle deviation reduced from 15.36 ± 17.57° to 4.21 ± 3.46° (p = 0.0275), and pitch angle deviation decreased from 6.17 ± 4.58° to 1.84 ± 1.48° (p < 0.001). The proposed vision-guided and modular jig system significantly improves the accuracy of pelvic bone tumor resections while maintaining workflow efficiency. This cost-effective solution provides real-time guidance without the need for referencing external monitors, potentially improving surgical outcomes in complex pelvic bone tumor cases.