The objective of this study is to examine the determinants of audit report timeliness in Nigeria. Specifically, the study examines the effect of company size, profitability, complexity and audit firm type on audit report timeliness. The cross-sectional research design was adopted with an extensive reliance on secondary data. The data was source from annual reports of manufacturing companies quoted on the floor of the Nigerian stock exchange for 2010-2012. The ordinary least squares (OLS) regression technique was utilized as the method of data analysis. The finding of the study shows the following; (i) A significant relationship exist between board size and Audit report lag (ii) A significant relationship exists between board independence and Audit report lag (iii) A non-significant relationship exists between audit firm type and Audit report lag. It was also discovered that the time lag prescribed by the regulatory bodies are usually too much thus encouraging companies to engage in the act of delaying their financial statements. The recommendation is that in achieving the objective of making the financial statements readily available for making timely decisions, the Nigerian stock exchange, securities and exchange commission, the Financial Reporting council, the Central Bank of Nigeria and other regulatory bodies should put in place measures to ensure strict compliance with the laid down rules and regulations.