Challenges and changes in the South African education system could have an impact on teachers' professional wellbeing, which, in turn, results in changes in teacher retention rates. The leadership of the school principal directly influences teachers' experience of professional wellbeing. Some research focuses on teacher wellbeing and plenty of research focuses on principals' leadership behaviour and leadership styles yet very limited research was found that links these two variables. In this research, the main aim was to explore the relationship between the principal's leadership behaviour and teachers' professional wellbeing improving teacher retention. The research design was a quantitative survey design embedded in the post-positivist paradigm. Two standardised instruments -- the Institute of Work Psychology Multi-Affect Indicator and the Multifactor Leadership Questionnaire -- were used to collect data among teachers from 20 selected schools in the Kenneth Kaunda District of the North-West Province of South Africa. Descriptive statistics and Spearman's rank correlations were used to analyse the data. The results showed a relationship between perceived leadership behaviour and wellbeing. Transformational and transactional leadership dimensions could positively contribute to teachers' professional wellbeing, whereas laissez-faire leadership has a potentially negative influence on their professional wellbeing. The use of transformational and transactional leadership behaviour results in teachers reporting positive job-related affective wellbeing, which can, in turn, influence teachers to remain in the profession due to their experience of enhanced professional wellbeing.