Megacities across the planet face a range of economic and territorial challenges. Future climate predictions suggest that several urban areas will present greater social and environmental problems in the coming decades, which makes strategic planning urgent and necessary for sustainable adaptation in all senses, i.e., economic, social and environmental. Some cities in the global south, such as Sao Paulo, had a history of rapid urban development without environmental planning throughout the 20th century, making urgent the need to expand green infrastructure, especially with the connection of forest fragments to the urban fabric. Therefore, this study aimed (i) to evaluate the increase in official urban parks throughout history, considering the spatialization and typologies of new parks in the territory of Sao Paulo, (ii) to understand the ecosystem services provided by urban forests and its distribution in the city, and (iii) to associate the temporal stability attributes of recent environmental secretaries with the officialization of protected areas in the city of Sao Paulo. The results revealed that only at the beginning of the 21st century was there an effective increase in the number of protected areas that shelter fragments of urban forests, contrasting the strong socio-spatial segregation that occurred in the 20th century with an economically vulnerable population that occupied peripheral areas with greater natural disaster risk. Political stability was a key factor for success in the environmental management of a megacity. The scenarios of environmental injustice reported in this manuscript can be revised with the implementation of policies and actions aimed at expanding green infrastructure in strategic sites, based on specific park typologies for each location. Such actions may come from public–private partnerships (PPP) that subsidize the socio-environmental transformation of the territory.