Green spaces contribute to aesthetics and environmental quality of life in urban areas. Kisumu City, the study area, has been experiencing demographic, environmental, economic, socio-spatial and institutional challenges leading to loss of green spaces. The main problem addressed by the study was dysfunctional use of green spaces leading to their loss, aesthetic value and low environmental quality. The study objective was to determine the effect of spatial change of urban green spaces on environmental quality. Data were both qualitative and quantitative and were collected through observation, interviews, questionnaires, photography, remote sensing and Geographic Positioning System (GPS). Qualitative research focused on site-specific analysis of urban and peri-urban neighbourhoods in Milimani and Nyalenda, respectively, which were purposively sampled. Results showed that area under green in 2005 was 44.8% while in 2004 it was 24.87% showing a decrease of 55.5%. However, in 2010, there was a temporary increase of green space of 51.82% due to demolitions to pave way for road expansion leading to decrease in carbon sink, resulting in increase in carbon footprint. This has led to low environmental quality. The study projects that by the year 2030, without proper planning interventions, the city will lose all its urban green cover. The research recommends the use of remote sensing for creating land-use inventory and monitoring systems. Citizen involvement in planning and management of urban green spaces is recommended because this will transform ecotourism in Kisumu City.