Smart city projects are designed to improve the quality of urban services, improve the efficiency of infrastructure, and increase the well-being of citizens. However, the success of these projects largely depends on their cost-effectiveness and financial efficiency. The present study, using a systematic literature review and library studies, examines the factors affecting the economic efficiency of smart city projects. The findings show that economic feasibility assessment, identification of initial costs, scalability analysis, and assessment of uncertainty of variables are the most important elements ensuring financial efficiency. Analytical tools such as MAFEIP and price sensitivity measurement (PSM) can determine the perceived value of users and the acceptable price range of services and help make efficient investment decisions. In addition, diverse financing methods including public, private, and public-private partnerships (PPP) play a key role in the financial sustainability and increasing the cost efficiency of projects. The results of this review show that integrating new technologies such as the Internet of Things (IoT) and appropriate financial models, in addition to increasing cost efficiency, can provide significant economic and social benefits for cities. This study can help urban planners and decision-makers to design and implement smart city projects in a cost-effective, sustainable, and efficient manner.