This study examines the influence of audit committee (AC) characteristics on voluntary corporate social responsibility (CSR) disclosure in the corporate annual reports of Australian listed firms. It develops hypotheses about the relationship between voluntary CSR disclosure and AC characteristics such as size, frequency of meetings, independence, independent chair, financial expertise and gender diversity. Using multiple regression analysis on data collected from the corporate annual reports of 300 listed firms, the study finds that AC characteristics such as size, frequency of meetings, committee independence and gender diversity have a significant positive influence on the level of CSR disclosure. However, there is no evidence that AC characteristics such as independent chair and members’ financial expertise affect CSR disclosure in Australian firms. Based on an additional analysis, the study also sheds some light on the effect of AC characteristics on environmental disclosure. The findings of this study may be of particular interest to regulators, shareholders, investment analysts and managers in assessing CSR disclosure in annual reports, and in strengthening the monitoring and oversight role of ACs.