Landfills and waste dumpsites are major sources of methane, carbon emission and other greenhouse gases (GHGs) within the ecosystem. However, efforts to convert these wastes to useful resource that could mitigate the emission of these gases are still daunting in developing countries particularly in Nigeria. This study assessed the management of solid waste in selected states of Southwestern Nigeria. The objectives of the study were to: (i) estimate the utilization index of solid waste; (ii) identify factors that affect waste utilization; (iii) examine the temporal pattern of waste utilization; (iv) identify differences in the use of virgin resources and waste on GHGs emission; and (v) estimate greenhouse gas emission saved due to the application of Reduce, Reuse and Recycle (3Rs).rnPrimary and secondary data were used in this study. The primary data were obtained using a structured questionnaire designed on a five-point Likert Scale. Ten recycling plants were purposively sampled in Osun, Oyo, Ogun and Lagos States at 5% level of significant. A total of four hundred copies of the questionnaire were randomly administered to the staff of the recycling plant at forty copies per recycling plants. The secondary data were obtained from the recycling plants inventories and checklist for a period of six years (2012-2017). Also, data were collected on quantity of waste generated and reused from waste management agencies in the selected states. Interviews were also conducted to understand peopleâ€™s perception on GHGs emission due to waste management concept of 3Rs. Both descriptive and inferential methods of data analyses were used. The descriptive methods used include tabulation, simple percentages, mean and standard deviation, while the inferential methods were relative index, multiple regression, factor analysis, trend analysis, two-way Analysis of Variance (ANOVA) and Waste Reduction Model (WARM).rnThe study finds that:rni. waste utilization index between 2012 and 2017 varied from 10-29%;rnii. environmental education, government policy, and benefits derivable from waste utilization accounted for 70.86% of the factors that promoted waste usage;rniii. there was a reduction of 50.654tons for plastic, 1.912tons for iron, 0.054tons for copper, 0.115tons for aluminum and 0.099tons for steel in waste utilization;rniv. reused waste was found to conserve more GHGs compared to virgin resource, while a significant difference exists (at F=0.021