ABSTRACT This study examined how ancillary functions mediate the relationship between pedagogical content knowledge (PCK) and teaching performance. It aimed to determine if involvement in ancillary functions is significantly related to both PCK and teaching performance. A predictive correlational research design was employed, gathering data from 201 teachers via a structured survey questionnaire. Statistical methods used included weighted mean, standard deviation, t-test, Pearson r, and the MACRO process. Results indicated that teachers perceived PCK levels are significantly related to teaching performance and involvement in ancillary functions. Moreover, the perceived extent of involvement in ancillary functions is significantly related to both perceived PCK levels and performance. The study found that involvement in ancillary functions partially mediates the relationship between perceived PCK levels and performance. Further research should investigate specific PCK components that influence teacher effectiveness and explore interventions and professional development programs to enhance teaching quality and student outcomes. Additionally, incorporating extra tasks into teacher training and professional development can help optimize task management. Providing teachers with the necessary resources, support, and training to manage ancillary tasks while maintaining their core instructional duties is also crucial. These recommendations aim to improve teaching effectiveness by balancing core instructional responsibilities with ancillary functions, thereby enhancing overall teaching performance and student learning outcomes. Keywords: pedagogical content knowledge, ancillary functions, teaching performance