Nigeria is facing some serious environmental challenges due to frequent oil spills, especially in the Niger Delta. Oil spills are one of the main sources of environmental contamination in the country. Daily oil spill incidents have polluted the air, soil, natural vegetation, farmlands, sources of drinking water, and fishing creeks. Multi endmember spectral mixture analysis (MESMA) was used to calculate vegetation percentage inside each pixel of Landsat7 images before and after oil spill incidents to evaluate the negative influence of spilled oil on impacted areas' vegetation. 163 recorded oil spill incidents between 2011 and 2012 were investigated in the Rivers State, Nigeria for this purpose. Results revealed that 73% of studied spill-impacted areas have vegetation losses caused by oil spills. Recorded oil spill data were used to create a comprehensive spatial database using GIS to examine which types of data could be potential determinants for oil spill influence on Nigeria’s vegetation. Among fifteen different types of examined oil spill data; this study concluded that impacted area size, spilled oil volume, residual oil volume on site, impacted area environment, and response, recovery, and cleanup timing are major determinants for oil spill influence on the Niger Delta’s vegetation.