Improving crop yields without increasing environmental costs is a key challenge for sustainable agriculture. Plastic film mulching (PM) is widely used because it effectively enhances crop production, but it can also cause persistent plastic pollution and increase greenhouse gas emissions. Degradable film mulching (DM) has been proposed as a promising alternative, yet its ability to maintain yield benefits while reducing environmental burdens remains unclear. Here we conducted four field experiments with three treatments: no mulching (NM), PM and DM. We further applied a calibrated Denitrification-Decomposition (DNDC) model to project future changes in crop yield and greenhouse gas emissions under PM and DM. PM and DM increased crop yield by 37.3% and 23.9%, respectively, but also increased global warming potential (GWP) by 36.2% and 11.4%, respectively. The calibrated DNDC model showed satisfactory performance. In the future period (2021-2100), DM reduced projected yield losses by 14.8-43.7% relative to PM and showed greater yield benefits associated with increases in temperature and precipitation. Moreover, DM reduced GWP by 14.0% under SSP1-2.6, 15.2% under SSP2-4.5, 17.4% under SSP3-7.0 and 17.2% under SSP5-8.5. These findings provide new evidence that DM could help reconcile the trade-off between food production and greenhouse gas mitigation in warm, humid regions, while improving adaptation to future climate change.