Sustainability reporting is an increasingly topical subject among companies, researchers and regulatory bodies. Awareness of the importance of sustainable business is becoming greater and more widespread, and the importance of sustainable reporting is constantly growing. In addition to the fact that sustainability reporting affects investors and the quality of information available to them for making business decisions, it also affects the social community and the way it perceives the organization. The concept of sustainability began to develop in the 80s of the last century, and until today its importance and applicability have been constantly increasing. The publication of the European Corporate Sustainability Reporting Directive (CSRD) in 2022 introduced a new way for auditors to approach annual corporate sustainability reports and introduced numerous new requirements and regulatory impositions. The publication of reports according to CSRD in the Republic of Croatia will begin in 2025 for the previous financial year, and from that moment the role of external auditors in revising sustainability reports will begin, since companies are obliged to ensure independent evaluation of reports. This paper explains the basic features and specifics of the CSRD Directive, such as its obligees by time period, how it expands the previous NFRD Directive, etc. The basis on which sustainability reporting in accordance with CSRD is based are the European Sustainability Reporting Standards (ESRS) which are a turning point in the form of sustainability reporting at the level of the entire European Union since they are mandatory. ESRSs are defined as standards that are a collection of all existing knowledge about sustainable reporting, and this is precisely the fact where their significance lies. Due to the auditor's role determined by the CSRD Directive, the paper analyses the required level of competence and expertise of external auditors, the importance and educational requirements in the field of sustainability. The types of assessment, i.e., the certification that auditors can issue in the form of a sustainability report, are explained, and the selection of the assessment of the Republic of Croatia is interpreted.