The purpose of this paper is to indicate the valuation importance of externalities derived from the urban ecosystem services (UES) in terms of their applicability in the appraisal process of urban regeneration projects co-financed from European funds. Specifically, it examines the impact of UES on the project's economic performance, and thereby on human quality of life. Using the discounted cash flow method, this paper estimates the project's economic performance indicators including the identified UES upon their prior valuation. The valuation was carried out on the basis of the benefit analysis, contingent valuation method-"willingness to pay" and benefit transfer method, as recommended by Bernaciak, Wojcieszak (2014) and Zawojska et al. (2016). Results show that urban projects including UES are characterised by the higher values of the economic performance indicators and they should be assessed higher than projects with little or no UES because of their stronger contribution to the sustainable development of urban areas. In spite of the fact that there are limitations due to the UES valuation techniques used in the study, the presented approach could be an important tool for the project's appraisal.