Green space (GS) is a central element of urban ecosystems while, urbanization is substantially changed green land into impervious ecosystems, which has then troubled the equilibrium of the surface thermal energy and the ecosystem services fluxes. This study was intended to explore the response of relative land surface tem-perature (RLST) intensities to the urban ecosystem-agglomeration dynamics as well as regional thermal envi-ronment (RTE) effects on green space in four major cities (i. e., Addis Ababa-Hawassa-Adama-Bahir Dar) of Ethiopia from 1990-2020, using a set of remote sensing images, single-channel algorism, and geospatial analy-ses. The results showed the trends of GS evolution were:GS loss>GS gain>GS exchange. Besides, the dis-tinct ecosystems as high-temperature zones (RLST more than 2℃) were gradually augmented and significantly intensified between 2010-2020 in all cities, while the proportion of green space was significantly decreased. Due to this, the segregated urban heat islands were gradually inter-weaved and interacted with each other and forming regional heat islands. However, the newly established green space has fewer cooling effects than ur-ban forest and greenery, because RLST of green space loss and gain are substantially disparate. We also con-firmed that the regional thermal environment is not only prejudiced by ecosystem patterns and processes be-sides substantially conquered by the particular GS change processes as well as RHI dynamics and evolution rate.