AbstractDigital information and data significantly improve the efficiency of government work in China. At the same time, in order to deal with information security and data leakage events, public departments have begun to pay attention to the information security awareness and behaviour of civil servants. Based on organisational culture and protection motivation theory, this study constructed a mediated moderation model to explore the influence mechanism of grassroots civil servants’ awareness of information security. This study collected 324 questionnaires from four regions of China. Results show that organisational culture has a significant positive impact on information security awareness. Professional identity has a significant positive effect on public service motivation and plays a negative moderating role in the relationship between organisational culture and information security awareness. Public service motivation mediates the moderating effect of professional identity on the relationship between organisational culture and information security awareness. The findings of this study offer practical implications and suggestions for further research.Points for practitioners The construction of organisational culture will effectively enhance the information security awareness of Chinese grassroots civil servants. Public departments should consider professional identity as an important factor when selecting grassroots civil servants engaged in information security work. In the implementation of information security management strategy planning, government departments can pay attention to and emphasise the public service motivation of grassroots civil servants.