Introduction: The aim of this study is to explore variables relating to teacher–student relationships, and their association with the detection of child maltreatment in secondary schools (12–18 age range), given that child and adolescent abuse is under revealed and underreported, and teachers play an important role in identifying and detecting it. Method: 662 teachers from secondary schools from different autonomous communities in Spain answered a self-administrated questionnaire. Results: This study revealed that while theoretical knowledge of the issue goes hand-in-hand with a higher self-reported ability to recognize cases among students, the same does not hold true of the teachers’ real detection capacity. Nonetheless, a relationship of trust with students and addressing child maltreatment in the classroom contributes to a better real detection capacity by teachers, relating this information to the possible existence of a teacher–student alliance. Discussion: We propose a trust-constructed relationship between both agents, named the teacher–student alliance. Prospective: These results point to the need for further research into the association and characteristics of teacher–student alliances on the identification in schools of cases of child maltreatment.