Aim: The main objective of the paper is to evaluate the scale, scope, and significance of investments in renewable energy sources by cities in Poland, which were co-financed from EU funds. This assessment will focus on the last two multiannual financial frameworks, namely for the years 2007–2013 and 2014–2020. Methods: Empirical studies were conducted based on data from the database of the Ministry of Development Funds and Regional Policy in Poland, the Local Data Bank, and the Ministry of Finance. When investigating the investment activity of towns and cities related to renewable energy sources, basic descriptive statistics methods were applied. Logistic regression was used to identify the primary socio-economic, financial, and environmental conditions. Results: In the analyzed period, the role of towns and cities in the realization of renewable energy projects increased, although it is still relatively limited compared to other types of administrative communes. In the multiannual financial framework for 2007–2013, less than one in ten cities executed at least one project, while in the years 2014–2020, more than one in four cities realized at least one project related to the development of renewable energy sources supported by EU funds. The disparity in activity between towns and cities on a regional scale was huge. These investments were more often realized by towns and cities with a lower level of development, serving tourist functions, and experienced in carrying out such investments. Their lower investment activity was influenced by their level of indebtedness. Conclusions: So far, one of the main drivers behind the development of renewable energy in urban areas has been the ecological aspect, particularly the improvement of air quality. However, there is now a growing recognition of the importance of energy security.