This study investigates the impact of Korean high school teachers’ perception of the benefits of participating in professional learning communities (PLCs) on teacher leadership using administrative survey data collected by the Gyeonggi Institute of Education. The findings indicate that positive experiences with PLCs can promote teacher leadership both within and beyond the classroom, highlighting the importance of providing professional development opportunities, collaboration and activities through PLCs. Furthermore, the study emphasises the crucial role of school culture, particularly positive school culture and supportive principal leadership in fostering teacher leadership both within and beyond the classroom. However, it also reveals that power dynamics and hierarchies in schools may negatively impact teacher leadership, particularly among female and non-tenured teachers in their beyond-classroom teacher leadership. Finally, the study shows that the innovative school status schools in Gyeonggi Province in South Korea has limited influence on the level of teacher leadership, or in some cases, may even have indicated lower levels of leadership compared to regular schools.