Our purpose in this research is to evaluate Seoul’s energy-transition policy for the last nine years and to suggest some policy-improving measures. Given the evaluation and recent carbon neutrality discussions in many countries, we also offer proposals for Seoul’s new energy vision and policy directions. 
Seoul has played a pioneering role in energy transition in South Korea since its initiation of the One Less Nuclear Power Plant (OLNPP) in 2012. With innovative policies, citizens’ support, and the strong leadership of Mayor Park, Seoul’s OLNPPP has largely been successful. It saved 6.87 MTOE of energy by means of active renewable energy, energy efficiency, and conservation policies. It also contributed to creating green jobs, increasing energy welfare, and broadening citizens’ participation. Further, the city’s diverse policies and programs were benchmarked by other local governments and influenced national energy policy. There is, however, several challenges that the city has to address to move towards more ambitious goals, such as carbon neutrality.
● Seoul needs to strengthen the building retrofit project (BRP) by introducing some binding regulations, such as emission caps and building-energy performance certificates, as well as offering more favorable financial incentives. 
● Building stock is an important asset for installing PVs in urban spatial settings. The current subsidy scheme needs to be changed to provide substantial financial incentives for kW-scale rooftop PVs. Mandating PVs on new buildings, as in New York city and France, also needs to be considered.
● Expansion of green industry is an indisputably effective way to create green jobs. In addition, it is also necessary to develop energy-business models in which people take part, such as energy cooperatives and prosumers. Retrofitting of low-income houses needs to be continued as a welfare-policy priority. 
● In order to mainstream the climate policy to all the policy areas of the city, the Headquarter of Climate and Environment needs to play a more active role with enough power and personnel. It is also necessary to collect data and develop ways to evaluate the effects of project implementation.
● The Seoul Energy Corporation, which currently is working on diverse business areas, ranging from renewable energy and district heating to smart energy and energy welfare, needs to strategically focus on priority business models and streamline the complex decision-making process. 
● Citizens’ participation needs to be broadened by empowering the district governments and communities. 
There are significant changes in the energy market and technology as distributed energy resources (DER) rapidly expand. In addition, the “Green New Deal” for 2050 carbon neutrality has become a new global norm for environmental policy. In this regard, Seoul’s energy-transition policy needs to be upgraded to embrace those changes and challenges. The new vision and policy directions are suggested as follows. 
● Seoul’s energy-transition policy needs to be restructured with a vision of 2050 carbon neutrality. To meet that bold target, stringent regulations, sufficient budget, and efficient organization should be prepared.
● In order to make a locally driven Green New Deal effective, energy decentralization that includes reform of governmental regulations, empowerment, and budget autonomy needs to be continuously promoted.
● Innovative and decentralized energy-market reform is required to accelerate the use of distributed energy resources and to foster new energy businesses. 
● Participatory governance is crucial to make the ambitious climate policy work.
● It is necessary to prepare safety measures for the people working in so-called “stranded industries”, such as for internal-combustion engines.