Hopwood argued that accounting has become associated with environmental concerns, and that environmental concerns will be further integrated into accounting practices in the near future. The McKinsey Company discovered that environmental information affects a firm's value, and that investors in firms with good corporate governance in Asian countries are willing to pay a price premium of 20 % or greater. The increasing need for environmental protection and responsibility to the community on the part of firms have led to environmental protection becoming a critical focal concern of governments, public welfare associations, and the public. Effective implementation of corporate governance has been reported to enhance operating performance and increase firm value. This study applies the Ohlson valuation model to examine the value relevance of environmental information disclosure and corporate governance, and investigate their on firms in Taiwan. The results indicate relationships between total disclosure of environmental information, mandatory disclosure of environmental information, and voluntary disclosure of environmental information and firm value. Corporate governance is positively correlated with the valuation of total disclosure of environmental information and mandatory disclosure of environmental information.