This study determined the influence of ISO 9001:2015 Quality Management System (QMS) implementation on service delivery and stakeholder satisfaction in the National Irrigation Administration (NIA) Region IV-A from 2025 to 2026. Specifically, it examined QMS dimensions such as process standardization and documentation, internal audit and corrective actions, risk management strategies, continuous improvement mechanisms, and employee involvement and training in relation to service delivery and stakeholder satisfaction. The study utilized a descriptive-correlational quantitative research design involving selected employees and stakeholders through stratified sampling. Data were collected using a validated structured questionnaire adapted from ISO QMS and service quality frameworks. Statistical tools such as mean and correlation analysis were used to analyze the data. Findings revealed that ISO 9001:2015 QMS implementation was generally evident and contributed to improved internal processes. Service delivery was rated satisfactory, while stakeholder satisfaction was generally positive. However, not all QMS dimensions showed significant relationships with service delivery and satisfaction, indicating that other organizational factors may also influence outcomes.