The world's population will be 9.2 billion in 2050, which is 2.2 billion more than today, with most of the increase in Africa, the Middle East, and South Asia. That will negatively affect the availability of arable land, infrastructure, and environmental performance of cities, furthermore, achieving sustainability pillars (environmental, economic, social) becomes mandatory for all countries after signing in the recommendation of the 2015 UN Summit, many initiatives and concepts were adopted to face these challenges and accomplish sustainable development. The green cities concept (GCC) and its strategies are considered an optimum approach to achieve sustainable development objectives and overcome these challenges, by enhancing performance for the existing infrastructure, reducing natural resource consumption, decreasing CO 2 emission, and engaging citizens in decision-making. On another hand, infrastructure projects are vital for achieving (GCC) concept because it reflects the progress and economic performance of countries. This study discusses the green cities, conventional and green infrastructure challenges, then presents Public-Private Partnership (PPPs) as a tool for implementing and overcoming its challenges from the green economy and green contracts perspectives. In addition, concluding an Operational Framework for implementing infrastructure projects by (PPPs) which determines the main phases in (PPPs), allocates the most important strategies for each phase, and indicates the main internal stockholders who share in decision-making. Finally, the study assigns ( 53) efficiency indicators and obtains a weight for each indicator by identifying the Relative Importance Index through an online questionnaire evaluated by (15) experts to track the achievement of the operational framework.