This study examined the effect of school workload on teaching effectiveness among ninety-one (91) teachers in the Panabo Central District. Specifically, it determined the extent of school workload in terms of duties and obligations, energy, and time management, as well as the extent of teaching effectiveness in terms of subject matter knowledge, instructional planning and strategies, assessment, learning environment, and effective communication. A descriptive-correlational research design was employed using adopted and validated survey instruments. Data were analyzed using weighted mean, pearson product moment correlation, and multiple regression analysis at a 0.05 level of significance. Findings revealed that both school workload and teaching effectiveness were at an extensive level, indicating that they were oftentimes evident among teachers. Results further showed a significant relationship between school workload and teaching effectiveness. Regression analysis confirmed that duties and obligations and energy significantly influenced teaching effectiveness, while time showed a weaker influence. The study concludes that workload management plays a critical role in sustaining instructional performance. Effective regulation of teachers’ responsibilities and support for their well-being are essential to maintaining high levels of teaching effectiveness.