In this study, paraelectric ceramics, (Ba0.85Ca0.15)(Zr0.10Ti0.90)1-x(Ni1/3Nb2/3)xO3, abbreviated as BCZT-xNN (with x=0.1, 0.2, 0.3, 0.4) were prepared via a solid-state reaction method. By introducing a B-site complex-ion, (Ni1/3Nb2/3)4+, the Curie temperature of the ceramic could be reduced to below room temperature. The effects of this B-site (Ni1/3Nb2/3)4+ complex-ion substitution on the phase structure, surface microstructure as well as the dielectric, ferroelectric, and energy storage properties of the ceramic were systematically investigated. After adding NN, BCZT-xNN shows a single phase perovskite structure without evidence of a second phase . In addition, we observed high stability with respect to both temperature (−55 to 160°C) and frequency (102–107Hz). Doping with NN produces slim polarization-electric field hysteresis loops and enhanced energy storage properties, while the efficiency decreases. When x=0.3, the highest energy storage density reached 0.66J/cm3 for a high electric field (20kV/mm), and the respective energy efficiency was 88.1%. These properties indicate that the environmental friendly BCZT-xNN ceramics are promising candidates for commercial energy storage devices.