The global expansion of urbanization is posing associated environmental and socioeconomic challenges. The capital city of Ethiopia, Addis Ababa, is also facing similar threats. The development of urban green infrastructures (UGIs) are the forefront mechanisms in mitigating these global challenges. Nevertheless, UGIs in Addis Ababa are degrading and inaccessible to the city residents. Hence, a 56 km long Addis River Side Green Development Project is under development with a total investment of USD 1.253 billion funded by Chinese government aid. In phase one of this grand project, Friendship Square Park (FSP), was established in 2019 with a total cost of about USD 50 million. This paper was initiated to describe the establishment process of FSP and assess its social, economic, and environmental contributions to the city. The establishment process was described in close collaboration with the FSP contractor, China Communications Construction Company, Ltd. (CCCC). The land use changes of FSP’s development were determined by satellite images, while its environmental benefits were assessed through plant selection, planting design, and seedling survival rate. Open and/or close ended questionnaires were designed to assess the socioeconomic values of the park. The green space of the area has highly changed from 2002 (8.6%) to 2019 (56.1%) when the park was completed. More than 74,288 seedlings in 133 species of seedlings were planted in the park. The average survival rate of these seedlings was 93%. On average about 500 people visit the park per day, and 400,000 USD is generated, just from the entrance fee, per annum. Overall, 100% of the visitors were strongly satisfied with the current status of the park and recommended some additional features to be included in it. In general, the park is contributing to the environmental and socioeconomic values of the city residents, and this kind of park should be developed in other sub-cities of the city as well as regional cities of Ethiopia to increase the aesthetic, environmental and socioeconomic values of the country, at large.