Currently, due to the growing dynamics of changes that take place in the environment of organizations, managers have to intensify their efforts to implement ‘solutions’ which will not only increase the efficiency of particular business activities, but will also strengthen the potential of the organization in the area of its sustainable development. One of the elements from a ‘wide set of potential solutions’ is risk culture. In spite of a number of studies dedicated to explaining its essence, dimensions and influence, the phenomenon of risk culture has not yet been fully explored. While the previous research and analyses have tended to focus on defining its role and learning about its effects, especially in the financial sector, this study was directed at explaining risk culture in the specific organizational context of implementing sustainable projects in business. This paper analyzes the manifestations of risk culture in sustainable projects, along with its dimensions and key determinants. The authors used the single case study method. In order to expose the Central European context, an innovative Polish enterprise with sustainable project management practices, implementing projects with a high degree of risk, was selected. The results of the study indicate that the main source of risk in the studied projects was the customer. Risk culture in this business entity is characterized by perceiving the variability of customer expectations as an important project risk factor. At the same time, sustainable project management ‘was accompanied’ by a more mature risk culture. The study confirmed that the beneficial impact of the risk culture on the project itself and the enterprise takes place under conditions of the convergence of the risk culture with the organizational culture. Conflicts between project participants, as well as conflicts between the project implementation team and the internal environment of the enterprise, increase the probability that risk culture poses a threat not only to particular projects, but also to the company.