This paper aims to construct a comprehensive corporate environmental responsibility (CER) engagement measurement to examine the relationship between CER engagement and firm value as well as explore the mediating effect of corporate innovation on this relationship based on a sample of 496 China's A‐share listed companies from 2008 to 2016. The results show that when firms start to adopt environmental regulations, CER would have a negative effect on firm value; however, at a specific level, CER would start to enhance firm value positively. In addition to this, corporate innovation plays a mediating role in the relationship between CER and firm value. Corporate innovation promotes firm value of firms with CER more than firms without CER. Overall, the findings of this paper are extremely relevant for the government, investors, and firm's managers and can be utilized for policy and investment decision making. Also, the findings encourage firms to enhance their sense of environmental responsibility in order to enhance their competitive advantages, enhance corporate innovation capabilities, and thus enhance firm value.