Organisational Citizenship Behaviour (OCB) has become an on-going important aspect in Human Resource Management. OCB is essential in improving organisations in terms of performance and productivity. The objectives of this study are two-fold: (1) to investigate the relationship among conscientiousness and organisational citizenship behaviour, and (2) to investigate the relationship among person supervisor fit and organisational citizenship behaviour. With this study, the negative outcomes of OCB can be reduced while enhancing the better outcomes of OCB. This study was applied among the employees in the finance and insurance industry in Kota Kinabalu, Sabah, Malaysia with a sample of 185. The participants were chosen in a purposive sampling method to ensure they are working in the relevant industry. A mono design that is a quantitative method was applied through google form questionnaires. This study is being formulated at a theoretical level and tested at an empirical level with SPSS 27 and SmartPLS 3.0. This study revealed that both conscientiousness and person-supervisor fit have positive effects on organisational citizenship behaviour. This study recommended that the Ministry of Finance should focus on the enhancement of organisational citizenship behaviour with the relation of personality and the fit between an employee and a supervisor.