The expansion of urban agglomerations and the accompanying increase in the severity of environmental problems require special attention to ensure a comfortable urban environment. One of the ways to solve this problem is to create an ecological framework in the megacity, formed by quasi-natural biocenoses, created within the application of the concept of rewilding. This article reviews the main current trends and approaches to the implementation of rewilding; discusses positive and negative environmental effects of the transformation of urban ecosystems within rewilding; presents an analytical review of available techniques and options for rewilding in various megacities around the world.