This study investigates how positive teacher–student relationships affect students’ behaviour and academic performance at an international school in Subang Jaya, Selangor. Using a mixed-method approach involving surveys (80 students and 20 teachers) and in-depth interviews (5 students and 5 teachers), the research demonstrates that supportive teacher–student relationships foster a conducive learning environment, enhance engagement and attendance, reduce behavioural issues, and lead to improved academic outcomes. Personalised support, mutual respect, and consistent communication emerged as essential elements in cultivating these relationships. Although the study is limited to one institution, it provides practical implications for educators and policymakers who aim to enhance student outcomes through strengthened interpersonal connections in schools.