Internal audit function (IAF) is a critical component of corporate governance mechanisms, and researchers have argued that internal audit effectiveness (IAE) is of utmost importance to serve the purpose. The study attempts to contribute to a better understanding on the role of audit committee (AC) characteristics (i.e. AC size, AC meeting frequency, AC expertise and AC independence) as a driver of IAE in public limited companies listed in Pakistan stock exchange (PSX). Two sets of questionnaires were distributed in 400 listed companies, whereas 162 completed sets in all respects with a response rate of 41% were received back. The collected data was analyzed using PLS-SEM. The results of the study indicated a positive influence of AC size and AC meeting frequency on the IAE of the listed companies. At the same time, the responses failed to establish any significant relationship between AC independence and AC expertise on the IAE.