Illegal, Unreported, and Unregulated (IUU) fishing continues to seriously threaten the sustainability of marine resources in Alicia, Zamboanga Sibugay, Philippines. However, nothing has been done yet to evaluate the IUU fishing in Alicia. This paper presents the first ever assessment of the vulnerability of coastal waters of Alicia to IUU fishing, using the Philippine IUU Fishing Index and Threat Assessment Tool (I-FIT) developed by DA-BFAR and USAID. The assessment focused on eight indicators with a scaling score from 1 (low vulnerability) to 4 (very high vulnerability) and a data quality score of 1-3 (low -high data quality). Alicia obtained a vulnerability score of 2.63, indicating a moderate risk to IUU fishing. This score is higher than the national average of 2.53. The key vulnerability factors include rich fishing grounds in the municipality that attract legal and illegal fishers, increasing prices of illegally caught fish, and a very low budget allocation for fisheries and coastal resource management. Yet, these are alleviated mainly by other factors such as well-defined jurisdictional borders and a combined enforcement pact with neighboring municipalities, as well as the absence of powerful groups defending illegal fishers. The data quality score is 3, denoting high data reliability. Recommendations include intensifying habitat protection, raising funding allocation, increasing enforcement operations, providing livelihood programs, monitoring, engaging community participation, and conducting regular vulnerability assessments. This study aligns with the Sustainable Development Goal Target 14.4, which seeks to end illegal, unreported, and unregulated (IUU) fishing. published by the Journal of Biodiversity and Environmental Sciences | JBES