The purpose of this study is to investigate the relationship between corporate governance practices and Indonesia’s SOEs' performance. State-owned enterprises (SOEs) are often criticized for underperformance and political manipulation, raising doubts about the efficiency of implemented corporate governance mechanisms. Additionally, this research examines the moderating role of board diversity on the relationship between good corporate governance (GCG) and performance. This study adopted a quantitative method to analyze secondary data from SOE’s financial statements from 2012 to 2019. The key independent variable is the GCG score, while return on assets is the dependent variable. The regression model incorporates managerial diversion variables and control variables. Surprisingly, the results found that corporate governance practices adversely affect the performance of Indonesian SOEs, particularly when board members have political affiliations. Institutional theory explains the negative relationship between the implementation of GCG and the performance of state-owned companies from coercive and mimetic perspectives. The phenomenon often happens in a developing country when a new system is adopted without fully understanding its mission. Additionally, the significant role of the Board of Commissioners' political connection as a moderating variable supports the conjecture of the managerial diversion perspective. This research contributes empirical insights for SOE stakeholders about corporate governance implementation and the performance of Indonesia's SOEs from the perspective of an emerging economy. The paper contributes novel views to agency and institutional theory for developing countries.