Objective The process of urbanization and industrial development have led to the increasing deterioration of the human living environment, and made the relationship between human and wild nature increasingly alienated. Scholars in the field of ecology and environment are aware of the necessity of urban rewilding and strive to restore the connection between human and wild nature in the city. Urban rewilding is a measure to restore the natural ecological process of the urban environment to protect urban biodiversity and enhance urban residents’ daily contact with wild nature. The discussion on the theoretical foundation for urban rewilding can provide theoretical reference for future urban greening construction and management.

Methods/process This research introduces the background and connotation of urban rewilding, summarizes relevant basic theories of urban rewilding, and explains the connections between such theories. These theories include urban ecology, rewilding, Nature-based Solutions (NbS) and biophilia, landscape ecology, biodiversity, community assembly, community succession, self-design and designer approach, invasion ecology, landscape disturbance and resilience, exposure ecology, and landscape preference theories. In order to show the organic connections between the aforesaid theories, this research sorts out these theories from the perspectives of urban ecosystem and rewilding, explains these theories from the perspectives of practice sector and elements of urban ecosystem, and analyzes and summarizes the schemes of urban rewilding and the theories corresponding to each step of the scheme. In addition, the research also explores the future research and practice directions of urban rewilding.

Results/conclusion Through a systematic analysis of the theoretical foundation for urban rewilding, the research finds that the theories discussed are organically related rather than mechanically combined. Thus, a systematic analysis and summary of the theoretical foundation for urban rewilding is made, which provides support for the establishment of a theoretical system of urban rewilding in the future and also provides ideas for academic research and applied practice in this field. The theories above are described in detail as follows. 1) Urban ecology theory. Urban rewilding needs to be based on a clear understanding of the city. The city is a complex social-ecological system. Urban rewilding is quite different from the rewilding of natural sites. 2) Rewilding theory. It provides an important reference for the research and practice of urban rewilding. 3) NbS and biophilia theory. Being closely related to rewilding theory, these theories have a reference role in the development of urban rewilding research. 4) Landscape ecology theory. For cities with different types of landscape patterns, the implementation strategies of urban rewilding will be different, and landscape ecology is needed as a large-scale perspective of urban rewilding. 5) Community assembly theory. The research on urban rewilding needs to be refined and conducted from a small-scale perspective. Only through community assembly theory can the actual state of rewilding in urban habitats be described. 6) Community succession theory. Community succession theory is needed to predict the future state of rewilded urban sites. 7) Biodiversity theory. The loss of urban biodiversity is the main reason for conducting urban rewilding research, and protecting biodiversity is an important goal of urban rewilding. 8) Self-design and designer approach theory. The self-design and designer approach of ecosystems are topics in the field of restoration ecology. Both are valuable for urban rewilding. 9) Invasion ecology theory. Invasion ecology is an important basic theory of urban rewilding, and it is promising to play an important role in the mechanical research and practice of urban rewilding. 10) Landscape disturbance and resilience theory. Disturbance is a neutral concept in the ecological community. The type, frequency, and intensity of natural disturbances that the urban environment can accept determine the degree to which the urban environment is close to the natural wilderness. 11) Exposure ecology theory. Urban rewilding is to expose urban residents to an environment with increased wilderness and enhance the health and well-being of urban residents. Exposure ecology theory is related to the verification of the health benefits of urban rewilding. 12) Landscape preference theory. Due to visual characteristics such as messiness and disorder, urban residents’ landscape preferences for wild environments may influence their acceptance of urban rewilding. Therefore, the research and practice of urban rewilding require theoretical foundations across varies scales and across natural and social sciences. Urban rewilding research can refer to research ideas and methods in related fields, such as applying information technology in the field of rewilding, verifying the impact of microorganisms on human health in urban rewilding research, and exploring the impact of urban ecosystems from an evolutionary perspective. The biggest challenge in urban rewilding may not be the theory or practice itself, but the development of theories that can guide practice — this is also a problem faced by the theoretical fields of related disciplines. Breakthroughs in the integration of theory and practice require quantitative cross-disciplinary research that can address the needs of multiple spatial and temporal scales. It also requires researchers themselves to have sufficient theoretical innovation capabilities and project practice experience. It is noteworthy that excessive beautification of the concept of urban rewilding will hinder the development and practical application of the theoretical system of urban rewilding. Objective exploration of the positive and negative impacts of urban rewilding is recommended. The implementation of urban rewilding requires adhering to the golden mean in traditional Chinese culture and maintaining a delicate equilibrium. City, ecology, or urban nature is not inherently good or bad. Therefore, urban rewilding is not a panacea that can bring absolute prosperity and vitality to cities. It is just a new stage in the human history of continuous contradictory struggle and compromise with nature. The research and practice of urban rewilding entail long-term efforts. By sorting out the theoretical foundation for urban rewilding, the research lays the foundation for the establishment of the theoretical system of urban rewilding, and provides ideas for academic research and application practice in this field.