The current trend towards promoting the conservation of ecosystems has resulted in various studies conducted to determine ways to establish an ecological network. As such, urban ecological networks challenge popular perceptions regarding green space planning and protection. They also emphasize the importance of green spaces as parts of an interconnected system for sustainable urban development. However, until now urban ecological networks have not been applied in urban planning. As a result, this study developed an urban ecological network planning (UENP) method based on urban ecology and landscape ecology theory in order to improve the stability of urban ecosystems. First, the evolving definition of an ecological network was examined. Next, the UENP model was established with a focus on green space and land management. Finally, as a case study, a UENP for northeastern cities within the Seoul Metropolitan Area was conducted.Policy implications of these results are also presented. The UENP developed in this study consists of three stages of analysis: 1) green space assessment for urban ecological stability, naturalness, and biodiversity with consideration to development risks; 2) development of an urban ecological network using least-cost path analysis; and 3) examination results with a land use plan to minimize possible conflict. As an approach in urban sustainability, the UENP suggested in this study can be applied to urban green network planning and be used to control urban sprawl and promote biodiversity.