The responsibility of companies to reduce the negative effects of climate change is obvious. The transition from a traditional linear economy to a circular economy means an increasing burden on companies. Besides the adequate financial performance, more and more emphasis is being placed on environmental performance. This study examines the non-financial sustainability reporting practices of 20 companies listed on the Bucharest Stock Exchange. The analysis used non-financial reports of companies with the highest market capitalization between 2020 and 2022. The analysis results support that the reports of environmentally sensitive companies are more extensive and detailed concerning investigated aspects. The details and length of the companies’ ESG (Environment, Social, Governance) reports increased during the three years examined. The environmental and social aspects of disclosed documents are more detailed for the banks, the oil extraction, and the telecommunication companies. In the company sample examined, it can be observed that most of the reports are prepared according to the GRI regulation. It can also be observed that the companies examined made more detailed and longer reports. The research results also support the fact that the aspects of the ESG report (E, S, G) also depend on the sector in which the companies operate.