<p>The aim of this study was to investigate the mechanical behavior of reinforced 3D printed concrete (3DPC) and to determine the effectiveness of different reinforcement types (steel cable, glass roving, steel mesh, glass mesh) under under different loading conditions. The mechanical behavior of the 3DPC was investigated using compressive, tensile, and four-point bending tests, with loading applied both along and across the printed layers. The study also encompassed the assessment of reinforcement properties, microstructural analysis of the reinforcement surface, and examination of the reinforcement-3DPC matrix bond strength. The results established that the compressive, tensile, flexural strength of reinforced 3DPC depends on the strength and deformation capacity of the reinforcement, the surface area of the reinforcement layer, and the reinforcement-3DPC matrix bond strength. It was shown that higher tensile strength in the reinforcing materials allows for a smaller reinforcement layer area to achieve a specified reinforced 3DPC strength. The effects of the reinforcement material’s strength and deformation capacity, the reinforcement layer area, and the reinforcement-3DPC matrix bond strength on the composite’s strength were identified. The effectiveness of structural reinforcement was assessed using the ratio of composite strength to its reinforcement layer area. This ratio can be used to select a rational reinforcement option for units within 3D printed structures, depending on the level and type of force impacts.</p>