There have been several financial scandals across the globe involving many big companies,and these have rocked confidence in the management of some of these companies.And in Ghana,this has not been uncommon,for several companies listed on the Ghana Stock Exchange,are engaged in financial mismanagement,which leads to their collapse.This has often brought up the question of the corporate governance structures existent in these companies and how they affect financial performance.The objective of this research was therefore to reach credible conclusions on the impact of corporate governance mechanisms in selected companies in Ghana on their financial performance.Companies were selected from the Ghana Stock Exchange and data collected on their published financial data as well as corporate governance metrics.The research also sought the mediating effects of financial disclosure and non-financial disclosure on the relationship between corporate governance mechanisms and financial performance of these companies.Data on the variables was collected from thirty-three（33）listed companies on the Ghana Stock Exchange（GSE）from 2008 to 2018.Based on the results of regression analysis,the dimensions of corporate managerial governance that we focused have different impacts on financial performance,and the research conclusions mainly include the following aspects.First,government intervention has significant and negative influence on financial performance,which means that corporation financial performance will decrease with the involvement of government in the list companies.Secondly,board independence has a significant positive impact on the company’s financial performance,which means that with the improvement of the independence of the board of directors,the company’s financial performance will also improve.Third,the impact of board size and board composition on the financial performance of listed companies in Ghana is not significant,which means that increasing board size and optimizing board composition can not bring higher financial performance.Fourth,non-financial disclosure plays a partial mediating effect on the relationship between corporate governance mechanism and corporate financial performance,while the mediating effect of financial disclosure is not significant,which means that the corporate governance mechanism of listed companies in Ghana improves corporate financial performance by strengthening non-financial information disclosure.The theoretical contribution of this research are as follow.First,based on the empirical study of Ghana listed firms,this paper reveals the influence of four factors of corporate governance mechanisms on corporate financial performance,which enriched the research results of corporate governance mechanism in developing countries.Second,this paper extends one step further by researching the mediating effect between corporate governance mechanism with the information disclosure and promotes a better understanding of corporate governance mechanism.Additionally,the empirical study based on the Ghana scenario provides Ghana’s evidence for the theoretical study of corporate governance in developing countries.