<p>Researchers have achieved remarkable control over material properties by designing novel architectures, particularly for tuning Poisson’s ratio. Despite abundant existing approaches, significant design space remains unexplored. This work presents two metamaterial designs exhibiting directionally dependent zero Poisson’s ratio, i.e., one-way zero Poisson’s ratio. In other loading directions, these metamaterials display positive or negative Poisson’s ratio. This selectivity stems from a mode switching mechanism between “unbuckling” and “buckling” of well-designed members within the metamaterials. Theoretical analysis reveals the conditions governing this mode switch, numerical simulation and experiments confirm the one-way Poisson’s effect. Furthermore, the high stiffness contrast within these buckling-prone members yields a pronounced asymmetry in equivalent moduli of the metamaterials under tension and compression, breaking the inherent symmetry of the elastic matrix of conventional materials. This asymmetry is then exploited to design metamaterial beams with asymmetric bending stiffness. Our findings and the design strategy presented here pave the way for developing advanced metamaterials with previously unattainable and unexpected Poisson’s ratios.</p>