The construction industry contributes significantly to global resource depletion, energy consumption, and environmental impact. Although 3D concrete printing (3DCP) reduces labour and formwork waste, its high cement demand raises environmental concerns. Recycled aggregates (RA) offer a sustainable alternative, but their use in 3DCP is still limited, especially in real-world applications. To address this gap, this study develops an integrated framework that combines life cycle assessment (LCA) and economic evaluation, applied to a full-scale 3D-printed structural unit using RA in Jiangsu, China. The analysis covers key phases such as material acquisition, construction, transportation, and assembly. Our findings reveal that while 3D printing reduces labour and eliminates the need for formwork, its overall environmental benefits are offset by the high cement usage and transportation emissions associated with the RA material. Sensitivity analyses indicate that optimising RA proportions and reducing transportation distances could enhance the sustainability and cost-efficiency of 3DCP projects. Although 3D printing has the potential to transform construction practices, significant improvements in material composition and logistics are required to fully realise its environmental and economic advantages. By using comprehensive real-world data, this study bridges the gap between laboratory-scale investigations and practical implementation, offering a robust foundation for evaluating the sustainability of 3DCP with RA. This study provides critical insights into the practical application of 3DCP with RA, moving the field closer to achieving sustainable large-scale construction.