Abstract: As a coastal-zone development control instrument widely used by coastal countries, coastal development setback lines provide an important basis for guiding planning and construction in coastal areas and occupy a key position in specialized coastal-zone planning. Because coastal zones involve multidimensional development needs, existing methods for delineating coastal development setback lines still have limitations in addressing multiple shoreline types and ecosystem protection. Responding to the spatial governance needs of coastal zones, this study strengthens the principles of land-sea coordination and ecological priority. Building on existing technical approaches, it introduces the concept of nature-based solutions (NbS), integrates multi-factor spatial overlay analysis, and constructs a technical method for delineating coastal development setback lines from an NbS perspective. The method is applied in Dalian, an important coastal city in northern China. The results show that, compared with previous approaches, the proposed method provides more comprehensive setback thresholds for complex shorelines in practical planning. It can offer technical support for coastal planning and management in Dalian and for the protection and sustainable development of coastal-zone ecosystems.