The purpose of this study is to examine the role of corporate governance in moderating the effect banking conglomeration on firm value. Using a samples of 84 firm years of banks listed in the Indonesia Stock Exchange during the 2011-2015 periods, empirical evidence of this study confirms the argument which is stated that banking conglomeration has positive effect on firm value. Of the four dimension of corporate governance are used in this study, this study finds that: (i) ownership monitoring and disclosure strengthen the effect of banking conglomeration on firm value, (ii) internal monitoring weaken the effect of banking conglomeration on firm value, and (iii) regulatory monitoring do not moderate the effect of banking conglomeration on firm value. This result has implication that banks need to strengthen their internal monitoring mechanism to supervise banking conglomeration’s activities effectively. For regulator, they should increase their regulatory monitoring, so their supervision can strengthen the effect of banking conglomeration on firm’s value.