While South Korea has early enacted legal systems—GPP Promotion Act (as of 1st July, 2005) led by Ministry of Environment (MoE)—to boost Korean’s GPP performance, the GPP growth rate has continuously slowed since 2015. On the other hands, Local Governments(LGs) are the most powerful consumers(actors) to reduce carbon emissions and resolve the climate change by procuring the eco-friendly products and services (eco-labelled products and services). Therefore, under this project, participant’s cities could directly and indirectly address sustainable issues and the green public procurement (GPP) would be a feasible tool to solve the climate change. Moreover, by forming the leading cities networks, they could construct the knowledge-sharing foundation to circulate the best-practices of GPP activities among Korean leading cities which can also lead to have a practical effect to participants’ surrounding regions. The ultimate goal of this project is to lead the Korean local governments to set the ambitious targets for GPP, reform the system and legal frameworks in a more innovative way, and establish collective-action system to deliver environmental issues both in national and international levels.