Given the significance of the coal industry and the associated environmental and safety challenges, the development of optimized extraction methods and effective management of gases produced during coal mining is imperative. This study investigates the effects of CO2 and CH4 adsorption and emission on the uniaxial compressive strength, elastic modulus, and axial strain of coal samples under various laboratory and macroscopic conditions. The results indicate that CO2 adsorption has a more pronounced negative impact on the engineering properties of coal, significantly reducing its strength. Specifically, CO2 adsorption and emission at injection pressures of 15 and 30 bar reduced the compressive strength of coal samples by 57.80% and 57.15%, respectively, and decreased the elastic modulus by 77.67% and 22.03%, respectively. In contrast, CH4 adsorption and emission at the same injection pressures reduced the compressive strength by 27.9% and 41.7%, respectively, and the elastic modulus by 18.06% and 19.91%, respectively. These reductions in engineering properties are influenced by parameters such as gas pressure, coal type, inherent fracture orientation and structure, moisture content, and other relevant factors. Based on these findings, the stability of coal pillars exposed to CO2 is compromised, necessitating careful consideration in the design and implementation of coalbed methane stimulation using CO2, as well as in CO2 sequestration projects in coal mines. Notably, the release of CH4 from both degassed and non-degassed gas-bearing layers also reduces coal strength, increasing the risks of coal outbursts, instantaneous gas emissions, and coal pillar instability.