Guidance and counselling services were introduced to Tanzanian schools as a strategy of ensuring social-psychological support to students and to ensure discipline in schools. Despite many years that these services have been in place, schools are still experiencing critical elements of indiscipline such as; truancies, sexual and drug abuse, unwanted early pregnancies, HIV/AIDS infection and students‟ dropouts. This situation has raised concerns about the effectiveness of guidance and counselling services on students‟ discipline in public secondary schools in Kwimba District which is the focus of this study. The study employed mixed research approach by which convergent research design and the Person-Centered Theory were used to guide the study. The participants were; the District Secondary Educational Officer, 5 heads of schools, 5 teachers-counsellors, and 90 form four students. Data collection was done by the use of questionnaires and interviews. Data analysis was based on themes and descriptive statistics with the help of Statistical Package for Social Science (SPSS). The findings from this study revealed that all the public secondary schools involved in this study were applying guidance and counselling services to manage students‟ discipline but were offered under discipline department. Furthermore, the study revealed that, guidance and counselling services have a positive influence on students‟ discipline. Moreover, the schools lacked guidance and counselling specialists, facilities and time for rendering guidance and counselling services. The study concludes that, guidance and counselling services are critically necessary means to enhance students‟ discipline in schools. The study recommends that, all stakeholders should play their roles effectively to improve the guidance and counselling services in schools.