This study investigates whether corporate social responsibility (CSR) alone sufficiently alleviates the problem of inefficient investment or not? This study considers firms registered on the Shanghai Exchange (China), Korean Exchange (South Korea)and Tokyo Exchange (Japan) for the period 2012 to 2016. Key findings are as follows. First, higher levels of CSR engagement have a positive role in alleviating investment inefficiency. Second, national culture plays a moderating role in the relationship between CSR and investment inefficiency for the entire sample. However, for China, national culture did not play any moderating role (weak culture). Korean national culture displays a partially moderating role (partially strong culture). Japan emerged as the strongest national culture because of the strong moderating role of its national culture. Third, information asymmetry has a mediating role between CSR and inefficient investment by solving the problem of underinvestment. Fourth, agency cost plays a mediating role between CSR engagement and inefficient investment by overcoming the problem of overinvestment. It concludes that CSR engagement alone is not sufficient for alleviating inefficient investment. However, the relationship between CSR and inefficient investment is explained more effectively, through the moderating effect of national culture and the mediating effect of information asymmetry and agency cost.