Urban areas are critical points that contribute to global warming and are also affected by climate change. One of the measures to move toward urban sustainability and to reduce the effects of climate change is the development of urban green infrastructures. Urban green infrastructures (UGIs) are being increasingly recognized as key providers of ecosystem services in cities, but there is still a lack of support from urban planners. We highlight the potential of urban green infrastructures for sustainable urban planning based on its capacity to mitigate climate change This paper studies the CO2 mitigation potential through a multi-intervention (agricultural and forestry) local case in the peri-urban surroundings of a big European city such as Madrid. We consider two inseparable aspects: the amount of atmospheric CO2-eq reduced through direct carbon uptake of the UGI and also the emission of greenhouse gases due to its implementation and maintenance. The analysis carried out has shown the benefits of urban green infrastructures and their contribution to the mitigation of climate change. The results demonstrate that the absorption capacity of the new urban green infrastructure is much greater than its ecological footprint. Therefore, it contributes to the mitigation of emissions from other urban activities, thus improving urban sustainability.