This study investigated the effect of work overload on the professional commitment of public sector nurses during the COVID-19 pandemic in the Kingdom of Eswatini (formerly Swaziland). Professional commitment is the degree to which an individual's psychological connection to their professional identity is strong. It predicts their motivation to remain in a professional role, to demonstrate professional dedication, and to champion the profession's values. Professional commitment is often sorely tested among public sector nurses, whose work is generally characterised by poor pay, intense, variable time pressure, work overload, and emotional stress. In Africa's public health systems, these challenges are exacerbated by poor working conditions, inadequate supplies, and critical staff shortages. During the COVID-19 pandemic, which further intensified these challenges, we collected data from a random sample of professional nurses (N = 417, 81% response rate). The initial analysis of the survey data showed high levels of professional commitment, and that work overload does not predict professional commitment directly. Additional analysis indicated that perceived work-family conflict mediated the relationship between work overload and professional commitment and that the effect of work overload on professional commitment, through work-family conflict, is moderated by supervisor support. The moderating effects of demographic variables such as age, marital status, and gender are also presented. Overall, the study's findings show a nuanced understanding of the effects of work overload on nurses' professional commitment, with attendant implications for management and staff training.