This study aims to examine the effect of organisational justice, professional commitment, and ethical leadership as moderating variables in predicting organisational citizenship behaviour (OCB). The advantage of the current study is the use of ethical leadership as a moderator in the relationship between organisational justice, commitment and OCB, as previous empirical studies are still limited. The population of this research is the academic community of private universities in Yogyakarta, Indonesia. Proportional stratified sampling was used for sample selection and research data were collected through questionnaires. Of the distributed questionnaires, 302 were included in the analysis. The results showed that organisational justice had a positive effect on OCB. However, when ethical leadership was included as a moderating variable, the interaction between organisational justice and ethical leadership was negative. In conclusion, ethical leadership weakens the relationship between organisational justice and OCB. The results also confirm that professional commitment has a positive effect on OCB. The interaction between professional commitment and ethical leadership as a moderating variable is negative. The conclusion is that ethical leadership weakens the relationship between professional commitment and OCB.