The main objective of the article is to evaluate the investment activity of large cities in Poland in the area of developing a low-carbon economy in 2014–2020, co-financed by European Union funds. This article poses several research questions, namely: Do large cities with environmental problems actively obtain EU funding to develop a low-carbon economy? What are the main socio-economic and environmental determinants of the level of the EU funding absorption among large cities in the research area? The empirical research was conducted on the basis of the data from the Ministry of Investment and Economic Development in Poland, which is responsible for the implementation of cohesion policy funds and from the Local Data Bank of Statistics Poland. Under the 2014–2020 perspective, 223 such projects have been implemented for a total of PLN 21 billion (EUR 4.74 billion). The projects focused on: transportation, electricity, gaseous fuels, steam, hot water and air for air conditioning systems, and environmental and climate change activities. In terms of both the number and the value of EU funds spent, great variation has been observed. Analysis of the correlation relationships showed a highly positive correlation between selected indicators of investment activity in the field of low-carbon economy co-financed by EU funds (especially taking into account the value of investments per area) and socio-economic indicators of Polish metropolises. Metropolises with high demographic, economic, and financial potential have proven to be more effective beneficiaries. Interestingly, no correlation was found between investment activity in the low-carbon economy and the level of environment pollution in large cities. This means that, unfortunately, pro-environmental activities depend on the state of finances of the cities, and not necessarily on the actual needs, even taking into account the fact that the EU covers a large proportion of the costs.