Microplastics (MPs), biochar, and earthworms are critical yet understudied drivers of greenhouse gas (GHG) emissions in agricultural soils. However, limited research has explored the interactive effects of these factors on soil GHG emissions and soil carbon and nitrogen cycling. Here, we conducted a full-factorial mesocosm experiment (2×2×2 design) to assess the individual and combined influences of PVC microplastics (1% w/w), biochar (1% w/w), and the epigeic earthworm on carbon dioxide (CO₂), nitrous oxide (N₂O), and methane (CH₄) emissions in a sandy-loam soil. The results revealed that MPs increased soil CO₂ emissions while suppressing N₂O and CH₄ emissions. Earthworms elevated CO₂ and N₂O emissions by 42.3% and 27.3%, respectively. Biochar amplified CO₂ release by 20.6% and reduced N₂O by 26.1%. The interaction between MPs and earthworms significantly influenced CO₂ emissions and the global warming potential (GWP). Both MPs and biochar significantly enhanced earthworm survival rates by 24-33% but did not affect individual biomass. Soil properties were partially influenced by the individual or combined effects of MPs, biochar, and earthworms. Overall, these results underscore the need for integrated amendment strategies to mitigate GHG emissions in MPcontaminated agroecosystems, balancing carbon sequestration priorities with soil health preservation.