Abstract: Growing concerns about greenhouse gas emissions from underground mining have intensified the need for carbon reduction strategies at every stage. Shotcrete used in tunnel support presents a promising opportunity for carbon emission reduction. This study investigates the carbon absorption capacity, mechanical strength, and underlying mechanisms of shotcrete when exposed to varying CO₂ concentrations during the mine support process. Findings reveal that higher CO₂ concentrations during the initial stages of carbonation curing enhance early strength but may impede long-term strength development. Shotcrete samples exposed to 2vol% CO₂ for 14 d exhibited a carbonation degree approximately three times higher than those exposed to 0.03vol% CO₂. A carbonation layer formed in the shotcrete, sequestering CO₂ as solid carbonates. In practical terms, shotcrete in an underground return-air tunnel absorbed 1.1 kg·m² of CO₂ over 14 d, equivalent to treating 33 m³ of contaminated air. Thus, using shotcrete for CO₂ curing in return-air tunnels can significantly reduce carbon emissions, contributing to greener and more sustainable mining practices.