NdBaMn2O6 exhibits a sequence of two following magnetic transitions: a second-order paramagnetic-ferromagnetic transition at TC = 290 K, followed by a first-order ferromagnetic-antiferromagnetic transition around TN = 210 K, leading to normal and inverse magnetocaloric effects (MCE), respectively. For ΔB = 5 T, the combined |−ΔSMmax| around TC and TN is found to be 2.5 J/kg K and 1.4 J/kgK, respectively. Moreover, the presence of these two −ΔSM peaks spanning over a broad range of temperature leads to a remarkably wide working temperature region, yielding a significant performance in terms of refrigerant efficiency. The present study demonstrates that adjusting the degree of A-site cation ordering in perovskite oxides is an efficient strategy to induce room-temperature MCE.