ABSTRACT A substantial body of research emphasizes the significance of trust in the relationships between school leaders and teachers. However, the organizational dimensions of trust, horizontal (trust in colleagues) and vertical (trust in the leader), remain underexplored, particularly concerning their role in supporting school leadership to develop a strong school culture. This paper examines the mediating role of horizontal trust and the moderating role of vertical trust in the relationship between learning‐centered leadership and collective teacher culture. A data set of 352 teachers from 43 lower secondary schools was analyzed using a multilevel structural equation modeling approach. The findings demonstrate that learning‐focused leadership influences horizontal trust and collective teacher culture. Learning‐centered leadership significantly contributes to creating a collective teacher culture through teachers’ perceptions of mutual trust. While vertical trust did not moderate the direct relationship between learning‐centered leadership and collective teacher culture, it was crucial in facilitating the relationship between learning‐centered leadership and horizontal trust. These results suggest that leadership has a larger influence on developing a collective teacher culture characterized by shared values and collaborative practices in schools with higher levels of trust in leadership.