Currently, the efforts of many cities around the world, including Seoul, are aimed at transforming themselves into smart cities under a governance vision. Thus, the purpose of this study is to propose a reinforcement plan for the ’Smart Seoul’ portal to develop into a cooperative, participatory, and network governance. We select four representative smart city portals from Barcelona, Amsterdam, Columbus, and Singapore and evaluate their main features and roles. We sort the features analyzed in each portal based on certain governance strategies, employing their key features as part of our evaluation criteria model. These evaluation criteria are used to analyze the ‘Smart Seoul’ portal and create a strengthening plan. The plan comprises a set of actions intended to improve the portal’s capabilities in terms of disclosure of information, the participation of stakeholders, and civil petition services. When this plan is implemented, the resulting optimal information disclosure through the ‘Smart Seoul’ portal will ensure the transparency of Seoul’s administration and create an environment in which citizens can actively participate in solving urban problems and making decisions. In addition, the results of this study will be an important guideline for the design and operation of smart city portals, and the catalogs for key features are expected to be used to make smart city portal design regulations in the future.