Urban environments are particularly affected by climate change impacts, such as Urban Heat Island (UHI), which leads to tangible consequences for the well-being and health of citizens. In this context, several national and international policies promote the implementation of Nature-Based Solutions (NBS) in urban contexts to provide a sustainable strategy for climate change mitigation and adaptation. However, the integration of these solutions into strategic urban planning remains a challenge, particularly due to the difficulty of evaluating their economic value. This study investigates the suitability of the Green Infrastructure Valuation toolkit (GiVal) as a preliminary tool for the economic assessment of NBS in urban environments. The tool has been applied for the economic evaluation of a reforestation project in the city of Milan, aligned with key goals of the city’s Climate and Air Plan. Based on the Benefit Transfer method, the GiVal tool estimates the economic value of a wide range of benefits. The proposed application underlines both the strengths and the criticalities of the GiVal tool. According to the obtained results and the recognised strengths and criticalities, it can be addressed that this tool is an effective preliminary evaluation framework which enables the identification of the benefits provided by the analysed NBS.