In this paper, we analyze the effect of shareholder activism on firm value through internal corporate governance in an emerging market. We investigate the shareholder activism by the National Pension Service (NPS) of Korea, the fourth-largest pension fund in the world in 2010. We investigate stock price reaction to a “vote no” press announcement and find that the market does not react in the short run, which reaction is inconsistent with the results from developed countries. We also find that firms experiencing “vote no” and improved internal corporate governance have higher firm valuation. Shareholder activism by the NPS is effective in increasing target firm value through improving internal corporate governance