Amid regional conflicts and widespread displacement, Arab schools face the challenge of teaching refugee and culturally diverse learners. This study examined how teachers’ cultural humility relates to multicultural teaching, considering the roles of religiosity and teacher agency. We conducted a cross-sectional survey of in-service teachers in Egypt (n = 234), Kuwait (n = 240), and Qatar (n = 214) (N = 688), developing and validating a teacher cultural humility scale alongside established measures of religiosity, agency, and multicultural teaching. Structural equation modeling supported a dual-mediation model; religiosity and teacher agency partly accounted for the association between humility and multicultural teaching, while a direct association remained (partial mediation). Religiosity emerged as the stronger mediator, suggesting that teachers’ moral and spiritual commitments provide a key bridge between humility and practice, complemented by their capacity to act adaptively through agency. Multi-group analyses indicated structural path equivalence across countries. Findings advance theoretical understanding of cultural humility in Arab educational contexts and underscore its practical importance for strengthening multicultural teaching in refugee-hosting schools.