The main purpose of this study was to examine the Contribution of professional codes of conduct on secondary education teacher’s professionalism: A Case of Bukoba District Council, Kagera Region, Tanzania. The study was guided by three specific objectives which are to examine the contribution of codes of ethics on teacher’s professionalism, to examine the contribution of moral development in education on teachers’ professionalism and to examine the contribution of ethical practice on teacher’s professionalism. The study was guided by deontological and utility theories. The research employed a mixed approach under convergent parallel research design. The study used a population of 149 comprising of 1 DSEO, 13 WEOs, 13 Head of Schools, and 122 Teachers. The researcher used questionnaires and interview guide for data collection. Data was obtained and analyzed using Statistical Package for Social Sciences (SPSS) version 20 computer package. The data used descriptive statistics and the findings were presented by use of frequency tables, pie-charts. Also, part of qualitative data coded, categorized and used thematic analysis of which description were employed to present data in chapter four. The study found out that professional code of conducts has much contribution on teaching professionalism. Furthermore, Moral values were found to be the key factor for the teaching professionalism. The study recommended that the government and other educational authorities to put more emphasize on the moral development to teachers because it contributes to ethical practice.