This research investigates the use of biochar as a supplement to natural aggregates in the development of 3D-printable concrete. Most studies on 3D concrete printing (3DCP) have focused on fine aggregates due to limitations in the printing system, particularly regarding the material delivery process. Pumping 3D-printable concrete with large aggregates poses challenges, as it requires larger nozzles and higher print speeds to accommodate the flow from the larger pumps, which typically have a higher flow rate than those used for fine aggregate materials. In this study, coarse biochar with a maximum size of approximately 10 mm was incorporated alongside natural coarse aggregates at volumes of 0%, 5%, and 10%. Various tests were conducted, including assessments of buildability, rheology, mechanical strength, and thermogravimetric analysis for carbon capture of the 3D-printable biochar materials, which were compared to reference materials without biochar. The findings showed that coarse biochar can effectively enhance early-age carbon sequestration while preserving printability. Although the addition of biochar reduced mechanical strength, a 5% biochar replacement achieved higher buildability. While biochar has traditionally been explored as a cement replacement or filler, its use as coarse aggregate in 3DCP is relatively new and has not been previously studied. Optimizing biochar derived from agricultural waste in concrete can further enhance the sustainability of current 3DCP technology. This approach provides a scalable strategy for integrating carbon capture functionality into digital construction materials.