The value of the financial flexibility factor is less addressed by the academic literature. This value is not directly visible to companies and should be measured and tested. This paper investigates the relationship between the value of financial flexibility, investment efficiency in net working capital and speed of adjustment of net working capital. This is an applied descriptive-correlational paper. The data were analyzed using the statistical population including 100 companies listed in the Tehran Stock Exchange for the period of 2005 to 2020. The multivariate linear regression method was used to test the research hypotheses. The results of the estimation of the regression model showed that there is a positive significant relationship between the value of financial flexibility and investment efficiency in net working capital and the speed of adjustment of net working capital. In addition, considering the value of financial flexibility factor in investment decisions can lead to more efficient investment opportunities and more optimal working capital policies for the company.