Today, more than half of the world's population of 7.6 billion lives in cities, and by 2030, it is estimated that the population of urban residents will exceed 5 billion worldwide. Since growth in cities causes the destruction of agriculture, forests, and wetlands, the increase in carbon footprint brings along many environmental problems, such as global climate change. Among the developing countries, Türkiye's largest cities have been experiencing a rapid urbanization process. The study aims to analyze the negative effects of urban growth in Türkiye's largest metropolises on natural areas such as agriculture, forests, and wetlands. The change process of the urban area has also been evaluated in terms of regulations and legislation. In this context, Istanbul, Ankara and Izmir metropolitan areas have been determined as case areas. The correlation between the changes in the land cover and the urban expansion processes of the three big cities from 1990 to 2018 has been systematically analyzed in the GIS environment using Corine Land Cover program data. The study indicates the devastating effect of urban growth on agricultural areas, in all three case areas. In addition, the urbanization pressure in Istanbul continues to destroy northern forests.