Express delivery services are booming in both developed and emerging economies due to their low cost, convenience, and the fast growth in online shopping. The increasing environmental impacts of express delivery services and mitigation potentials, however, remain largely unexplored. Here we addressed such a gap for China, a country which is expanding online retail sales and express delivery rapidly. We found a total of 8.8 Mt of scrap packaging materials were generated by the express delivery sector in China in 2018. Its transportation-related GHG emissions surged from 0.3 Mt in 2007 to 13.7 Mt of CO2-equivalent (CO2e) in 2018, with an average of 0.27 kgCO2e per piece. Over 80% from online shopping deliveries. We predict these emissions will reach 75 MtCO2e by 2035. Nevertheless, it is possible to mitigate such GHG emissions by 102~134 MtCO2e between 2020 and 2035 if a suite of policies is adopted, including a slowdown of delivery speed, fuel system upgrades, packaging materials reduction, logistics optimization, and carbon pricing.