Telementoring is a low-cost, flexible way for school mental health professionals to access professional learning. Using a mixed-methods intervention design, we examined the impact of prolonged telementoring on school mental health professionals' (school counselors, psychologists, social workers, and others) understanding and application of evidence-based school counseling, including associations between their use of evidence-based, culturally responsive, and collaborative practices to support student mental health. Our findings demonstrate support for the use of telementoring to improve school mental health professionals' understanding and application of the evidence-based school counseling model. We provide specific considerations for school counseling professionals.