Sustainability Reporting includes a large scope of topics that affect many aspects of a company. It has been applied by companies for over 20 years and has gained great recognition since 2000. Nowadays, and especial due to the accelerating climate change that we witness, Corporate Social Responsibility (CSR), Non-Financial Reporting (ESG – Environmental, Social, Governance) and Corporate Environmental Sustainability Reporting (CESR) have become crucial issues for companies and governments. In this paper, it is discussed how these issues became crucial for companies and societies and how the European Union acts for enhancing them. Also, this paper analyzes the implementation practices, meaning the tools used for applying the sustainability reporting, with emphasis to the GRI Standards. The importance of this kind of reporting stimulates research into the benefits and the necessity of its implementation. In the second part, we refer to the Greek legislation and we examine the case of the Athens International Airport (AIA), Eleftherios Venizelos, the Corporate Responsibility Report 2016 of which is further examined. The focus is on what is reported, how it is applied and what are the benefits of reporting for the company, the society and the environment. Finally, we track the gaps and suggest further investigation as far as small medium companies are concerned.