To achieve corporate sustainable performance, a company must go beyond the simple compliance to the legislative requirements. In this context, eco-innovation plays a key role in achieving global sustainability goals and objectives of organizations, especially those related to the environmental component of sustainability. While most researchers have given considerable attention to the various methods and tools directed at measuring eco-innovation and sustainability at the macro-economic level, very few studies deal with these metrics at the micro-economic level. In this context, the purpose of this paper is twofold. Firstly, after a thorough literature review, it will offer a clear presentation of the main indicators used in assessing corporate sustainability and environmental performance of organizations, with an emphasis on eco-innovation. Secondly, the paper will harness the results of a questionnaire-based study developed by the authors among companies operating on the Romanian market to identify their preoccupations for eco-innovation and for assessing environmental performance via indicators. The authors also provide examples of environmental sustainability metrics from the analysis of sustainability reports of several sample companies active in the construction, oil and gas, fast moving consumer goods, telecommunications and banking sectors. These serve to illustrate the diversity of sustainability metrics used to assess environmental performance, rather than as examples of best practice. The exploratory questionnaire-based research findings confirm the international sustainable development trend, as an increasing number of large, medium and small enterprises active in Romania started to incorporate sustainability into their business strategies. However, many of the organizations participating in the research do not assess the environmental performance and have no clear evidence of the costs involved, nor a precise monitoring of the results associated with the implementation of sustainability measures in the business strategy. Therefore, the authors argue for the importance of creating a framework and selecting appropriate indicators that quantify sustainability and environmental performance, and make suggestions for developing such a framework. The value this paper lies in approaching an innovative subject, in the context of a lack of consolidated data on eco-innovation and corporate sustainability metrics. Furthermore, the article has numerous practical implications, as it represents a useful source of information for practitioners interested in the field.