The study examined the influence of international financial reporting standards on financial performance and taxation of five selected firms each from consumer goods, industrial goods and banking sectors in Nigeria between the period of 2009-2011 and post IFRS adoption period (2013-2020). The specific objectives of the study were to examine the effect of profitability of listed firms and IFRS adoption on taxation of selected firms in Nigeria. The study was anchored on agency and signaling theories. We employed descriptive statistics and paired sample t-tests in the analysis of data. Our findings show that mandatory adoption of IFRS has a significant impact on profitability of listed firms in Nigeria while IFRS has an insignificant impact on taxation of selected listed firms in Nigeria. There were no significant differences in the impact of IFRS adoption on profitability assessment between the key sectors of listed firms and there were no significant differences in the impact of IFRS adoption on taxation between the key sectors of listed firms in Nigeria. It was concluded that IFRS adoption has a significant possible impact on profitability and that taxation is significantly affected by IFRS adoption. Also, significant differences do not exist between the impact of IFRS adoption on the key sectors of listed firms in Nigeria, namely; consumer goods, industrial goods and the banking sectors. The study recommended amongst others that corporate managers should ensure compliance with IFRS since it positively impacts on profit.