Beef cattle and poultry are critically important livestock for improving household food security and alleviating poverty amongst smallholder farmers in South Africa. In this paper, our goal is to examine the relationships between farmer psychological profiles and farm business performance of commercially oriented beef cattle and poultry smallholder farmers in South Africa. We employ a multipronged interdisciplinary approach to test the theory of planned behaviour and its relationship to farm business performance. First, a behavioural science-informed survey instrument was employed to collect data from randomly selected farmer participants in two major beef and poultry projects undertaken by the authors. Second, a latent profile analysis was used to identify the psychological profiles of those farmers. Third, traditional and estimated indicators of farm business performance were obtained using descriptive and econometric-based approaches, including logistic regression and stochastic frontier analyses. The estimated farm business performance indicators were correlated with the psychological profiles of farmers. Results from the latent profile analysis showed three distinct profiles of beef and poultry farmers clearly differentiated by their ability to control and succeed in their farm business enterprises; criteria included attitude, openness to ideas, personality, perceived capabilities, self-efficacy, time orientation, and farm- and personal-related concerns. Profile 1 ('Fatalists') scored themselves negatively on their ability to control and succeed in their business enterprises. The majority of farmers were generally neutral about their ability to control and succeed in their businesses (Profile 2, 'Traditionalists'), while a relatively small group of farmers were confident of their ability to succeed (Profile 3, 'Entrepreneurs'). We found evidence of significant differences in farm business performance amongst the different profiles of farmers. As far as we can determine, this is the only study to have assessed farm business performance based on a differentiation of farmers' psychological profiles. Our results provide a framework to further investigate whether particular types of on-farm interventions and training methods can be customised for different segments of farmers based on their preferred learning styles.