This study aims to investigate the commitment of public shareholding companies in the service sector to apply Corporate Governance (CG) principles. It aims also to clarify the relationship between the practice of CG in the service sector and effectiveness, and the relationship between the practice of CG and the value of these companies. The study sample consists of all service companies listed on the Amman Stock Exchange (2016-2018) which were (54) service companies that meet conditions. Multiple regression analysis was used to test the effect of independent variables (ownership concentration, and the independence of the Board of Managers) on dependent variables (market value to book value, market value to net income, and turnover of assets), The researcher also used the test of the presence of the phenomenon of multiple linear correlation Collinearity by testing the significance of the correlation coefficient between variables, The researcher used Independent-Sample and One-Sample t-t