Sustainability has evolved into one of the major challenges for society as a whole and for the business world. This changing perception over the past two decades has resulted in increased requirements for corporate sustainability. In order to meet stakeholders’ desire for information, documenting the corporate contribution to sustainability becomes an important aspect of companies’ stakeholder communication. Especially the real estate industry bears a high level of responsibility, since this sector is regarded as one of the major triggers of anthropogenic climate change and resource exploitation, making sustainable corporate management and the communication thereof quite essential. As the leading authority in sustainability reporting, the Global Reporting Initiative (GRI), published an internationally recognized common framework, in order to ensure the comparability and standardization of corporate sustainability reporting. This paper analyses, for the first time, whether sustainability reporting has an influence on the stock prices of real estate companies. Using the methodology of event study, research with a global sample (Europe, USA and Australia) shows a clear positive impact. Thus, sustainability and its communication do indeed have an impact on corporate valuation, so that efforts to promote corporate sustainability cannot be branded simply as altruism. In fact, sustainability is of decision-making relevance for shareholders and investors and therefore constitutes a success factor for companies. The results of this study provide empirical evidence based on data from listed real estate companies.