This study examines the impact of corporate governance (CG) practices and ownership structure on idiosyncratic volatility using the sample of 100 non-financial firms listed at the Pakistan Stock Exchange for the time period of 2003-2017. Agency theory suggests that good governance practices can enhance transparency and reduce asymmetric information which leads to decrease the risk of the firm. This study uses idiosyncratic volatility index as a dependent variable, which is measured by cash flow volatility, sales volatility and earning per share volatility, whereas Corporate Governance attributes, institutional ownership, family ownership and managerial ownership as independent variables. Using the GMM model, this study shows that CGI and family ownership both have a negative association with idiosyncratic volatility, whereas institutional ownership and managerial ownership are both increases idiosyncratic volatility of firm in Pakistan. It is concluded that quality CG practices can decrease the idiosyncratic volatility of firms. This result of the study may helpful for firm managers, investors, shareholders, risk managers and policy-makers. Supervisor: Dr. Abdul Rashid Co-supervisor: Dr. Farhat Mahmood