Illegal dumping of waste persistently threatens environmental sustainability and public health in the CALABARZON region (Cavite, Laguna, Batangas, Rizal, and Quezon), despite the Ecological Solid Waste Management Act and regional waste management initiatives. Rapid urbanization, uneven enforcement, and limited sanitary landfill capacity leave monitoring efforts reactive, sporadic, and resource-constrained. Building on a previously developed graph-based anomaly detection model, which identifies spatial and temporal irregularities in waste disposal patterns from satellite and infrastructure data, this study applies its outputs to develop a decision-support tool for prioritizing illegal dumpsite inspections in CALABARZON. This study introduced the Dumpsite Inspection Priority Index (DIPI), a geospatially grounded, expert-informed decision-support framework to prioritize inspection of illegal dumpsites across the region. Using Decision-Making Trial and Evaluation Laboratory (DEMATEL) method, six spatial and contextual factors were identified and weighted, including proximity to residential areas and frequency of illegal dumping of waste, through expert consultations and spatial datasets: Sentinel satellite imagery, OSM infrastructure data, and monitoring records. Results from computed DIPI scores across 28 sites revealed that 46% fall under High to Critical Priority, indicating widespread but uneven risks. Notably, sites in Batangas, Quezon, and Laguna exhibited both high and low priority levels in proximity, implying localized disparities in land use practices and enforcement. The DIPI enables a transparent, data-driven prioritization tool, addressing inefficiencies in the current framework. To maximize its impact, the study recommends integrating DIPI into centralized digital platforms, addressing data and technological gaps, and strengthening inter-agency coordination to enhance the responsiveness and sustainability of waste governance.