We present combined experimental and theoretical investigations on the magnetic and magnetocaloric behavior of Nd$_2$NiMnO$_6$. The relative cooling power (RCP) which quantifies the usefulness of a magnetocaloric (MC) material is estimated to be $approx 300$ J/Kg near the ferromagnetic transition at $T_C approx 195$ K. This RCP is comparable to the best known MC materials. Additionally, the magnetic entropy change has a broad profile ($T_C - 50~{rm K} < T < T_C + 50~{rm K}$) leading to an enhancement in the working-range of temperatures for magnetocaloric based cooling. These features make Nd$_2$NiMnO$_6$ a superior magnetocaloric material compared for example, to the nonmagnetic counterpart Y$_2$NiMnO$_6$. We identify the mechanism for the enhanced RCP which can guide search for future MC materials.
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