Despite the time taken by external auditors to release the audit report (herein referred to as the auditor report lag, ARL) being regarded as a significant qualitative aspect of timely financial reporting, little known about the determinants of ARL in listed companies in developing economies. This study sought to investigate the determinants of ARL in companies listed in Kenya. A descriptive research design was used to study the auditor-related factors, company-specific factors and corporate governance factors affecting ARL. Two-stage panel least squares regressions were performed to establish the drivers of ARL. The study focused on a ten-year period from 2006 to 2015. The findings revealed that auditor type was the most significant auditor related factor that was associated with ARL. In terms of company-specific factors, the return on assets (ROA) was significant and negatively associated with ARL. In terms of industry sector, the study found that listed companies in the banking sector had lower ARLs. Similarly, companies in the manufacturing sector had lower ARLs. The study found that listed companies in the investment sector had longer ARLs. Next, the study found that listed companies with a higher corporate governance score had shorter ARL. The findings revealed that there exists auditor-specific, company-specific and corporate governance influences on ARL. To corroborate findings from secondary data, semi-structured questionnaires were used. The findings from the questionnaires demonstrated that alongside auditor-, company- and corporate governance-related factors, there are also regulatory factors influencing ARL. The findings should be of interest to managers, auditors and policy makers because these results may help the assessment of the influence of such variables on improving the timeliness of audit reports. Despite the study focusing on ARL in a single country-setting, it contributes to the sparse literature of drivers of ARL in developing countries.