Global climate change and rising CO2 emissions highlight the need for sustainable carbon capture technologies. Biochar, with its porous structure and high adsorption capacity, shows promise as a CO2 adsorbent. This study enhances coffee waste-derived biochar through ZnCl2 activation and MDEA functionalization, assessing its feasibility in cementitious applications. The characterization of biochar confirmed structural and functional modifications through CHNS, FE-SEM, and FTIR analysis. Mechanical strength and carbonation depth measurements were conducted on biochar-incorporated mortar. The experimental results confirmed the successful activation of biochar and the effective incorporation of MDEA. Mortar testing demonstrated changes in mechanical properties and an enhancement in carbonation sequestration capacity. These findings highlight the potential of chemically modified biochar as a sustainable cementitious material, offering a promising approach for enhancing CO2 sequestration while maintaining structural performance.