Greater Cibinong, a buffer zone of Jakarta, has experienced rapid population growth leading to the conversion of green areas into built-up zones. This transformation affects ecological balance, reduces air quality, and worsens climate change. As land availability for Green Open Spaces (GOS) becomes increasingly limited amid rapid urbanization, understanding the extent of GOS ecological functions in providing landscape services is crucial. Aims: This study aims to analyze the ecological functions of GOS in delivering landscape services, including carbon sequestration and storage, pollution absorption, and rainfall interception. Methodology and results: This study applies the i-Tree Canopy method using a random point sampling technique with 500 sampling points across six subdistricts in Greater Cibinong. The number of samples is set to achieve a 95% confidence level with a margin of error below 1.6%, meets this tolerance. Conclusion, significance and impact study: GOS play a vital role in maintaining ecological functions. Babakan Madang Subdistrict recorded the highest vegetation cover (tree/shrub) at 60.24%, with annual carbon storage of 16.99 kt (equivalent to IDR 134.46 billion), pollution removal of 491.19 tons per year (equivalent to IDR 23.62 billion), and runoff reduction of 183.86 ML (equivalent to IDR 7.19 billion). In contrast, Bojong Gede Subdistrict showed the highest impervious building cover at 43.80%. The most absorbed pollutants were ozone (O₃) and PM₁₀. The findings highlight the significant contribution of GOS to climate change mitigation, air quality improvement, and hydrological regulation, emphasizing the need for more effective policies on GOS protection and management.