This paper aims to examine the effect of audit committee characteristics on audit report lag, and also explores whether this effect will vary between before and after mandatory adoption of IFRS in Saudi listed companies. Based on a Saudi sample of 388 firm-year observations from 2015 to 2018, the Poisson regression analysis shows that among audit committee characteristics, only audit committee financial experience significantly influences the timing of financial reporting. The result indicates a weak influence of audit committees on timeliness of financial reporting, which is consistent with the results of most of previous studies. On the other hand, the results show a strong impact of the adoption of IFRS on the context of that relationship, where the results show the impact of IFRS on audit report lag, audit committee quality and the association between them.