In recent decades, with the rapid growth of urbanization, the amount of carbon emission in urban areas has been globally accelerated. In this study, the carbon storage capacity of different small administrative regions (wards) of Khulna city has been estimated based on four major sinks types- trees, vegetations, soils, and water bodies. To estimate carbon storage capacity, the total coverage area of each of the sink’s types has been estimated by Sentinel-II satellite image data of 2019 through supervised image classification of remote sensing techniques. A comparison of more carbon-absorbing capacities between the wards has been assessed through GIS techniques as well. Results show that the north-west part of Khulna city has some extent of carbon sinks. However, the lower portion in the southern part is congested with built-up areas and has a huge lacking of carbon sinks. The obtained amount of carbon about 9306992 kg, 7733698 kg, 7328298 kg, and 6030692 kg have been absorbed through respective trees, vegetations, soils, and water bodies which is about 31%, 25%, 24%, and 20% of total absorption, respectively. The result shows that carbon absorption capacity is very high in ward no. 3 whereas ward no. 1, 2, 4, 6, 9, 14, 16, and 31 are high carbon-absorbing wards. Ward no 8, 13, 15, 17, 18 and 24 are moderate, ward no 5, 10, 12, 21, 22, 25, 26, 27, 28, 29 and 30 are lower and ward no 7, 11, 19, 20 and 23 are very lower carbon-absorbing wards of Khulna city. The findings of this study opt to provide valuable insights amongst significant stakeholders, i.e., local people, urban planners, policy-makers, and non-government organizations regarding the emission and absorption of carbon.