The major objective of the research is to examine the relationship between the corporate characteristics of firm age, audit firms and tax rate on the one hand and environmental reporting on the other, through environmental policy administrators.The study considers environmentally sensitive firms listed in the NSE for the 6-year period ranging from 2009 to 2014. Data of the selected sample were analyzed using Stata13 to produce statistical results. The outcome of evaluated data was very encouraging as it shows an average disclosure rate of 60.36% given by the simple average disclosure index. Besides, the discovery also pointed out that a significant relationship exists between corporate characteristics and sustainability reporting. Environmental reporting should be made mandatory and an effective and efficient enforcement of G4 be done, so that the positive trends in environmental reporting could be maintained and sustained. An analysis of the moderating influence of environmental protection agencies on environmental disclosure due to corporate characteristics and the test of G4 in a developing and Africa‟s largest economy is a new experience. The study was restricted to only environmentally sensitive firms listed in the NSE. Future studies could be extended to an entire economy and even make comparison with developed or other emerging economies.