Behavioral problems among students are increasingly recognized as significant challenges in the current educational system. School guidance and counseling services play a crucial role in managing these behaviors and promoting students’ social and academic development. This study aimed to examine the role of school guidance and counseling services in students’ behavioral adjustment in Tamilmedium schools within the Colombo Central Education Zone. Specifically, it investigated the operational status of the services, their relationship with students’ behavioral adjustment, and the impact of different service components on behavioral dimensions. Embeded mixed-method research approach, integrating quantitative and qualitative techniques, was employed. The study population consisted of students participating in guidance and counseling services in the targeted schools, with a sample of 80 students selected using purposive sampling. Additionally, 8 counselors and 8 principals were included as key informants. Data were collected through questionnaires and interviews and analyzed using statistical methods for quantitative data and thematic analysis for qualitative data. The findings revealed that students held moderately positive perceptions of guidance and counseling services. Among service components, counselor qualification received the highest mean score (M = 3.78). Regarding behavioral adjustment dimensions, interpersonal relationships scored highest (M = 4.18), while self-management scored lowest (M = 3.41). A moderate positive correlation (r = .506, p < .001) was observed between overall guidance and counseling services and students’ behavioral adjustment. Further, facilities provided for counseling (β = .32, p = .015) and counselor qualification (β = .28, p = .046) emerged as significant predictors, collectively explaining 31% of the variance in behavioral adjustment. The study concludes that school guidance and counseling services significantly influence students’ behavioral adjustment. Moreover, the dual role of the counselor and the time limitations for counseling sessions have an impact on the behavior of students. ,In its fundamental, guidance counseling services have a significant impact on the behavior of students, Services delivered by qualified counselors with adequate facilities yield better outcomes. Consequently, it is essential to enhance counseling infrastructure, ensure counselor qualification and competence, and implement programs to improve students’ self-management skills. Strengthening infrastructure, professional training, and administrative support are essential steps toward improving counselling service effectiveness in Sri Lankan schools.