In this work, novel (1− x)(0.75Na0.5Bi0.5TiO₃)-0.25Sr(Zr0.2Sn0.2Hf0.2Ti0.2Nb0.2)O₃-xNaNbO₃ (NBT-SZSHTN-xNN,x = 0.1, 0.15, 0.2, 0.25) ceramics were fabricated. The influence of co-doping of NN and high entropy perovskite oxide (SZSHTN) on the phase structure, microstructure and dielectric properties of NBT-based lead-free ceramics was investigated. Dense microstructure with a grain size of∼5μm is observed. Whenx = 0.25, a wide dielectric temperature stable range of − 35.4–224.3∘C with a low temperature coefficient of capacitance of< 10% is achieved, fulfilling the industry standard of Y9P specification. Furthermore, excellent energy storage performance with recoverable energy density of 2.4 J/cm³, discharge efficiency of 71%, power density of 25.495 MW/cm³ and discharge rate< 200 ns are simultaneously obtained, which shows great potential for high temperature capacitor applications.In this work, novel (1− x)(0.75Na0.5Bi0.5TiO₃)-0.25Sr(Zr0.2Sn0.2Hf0.2Ti0.2Nb0.2)O₃-xNaNbO₃ (NBT-SZSHTN-xNN,x = 0.1, 0.15, 0.2, 0.25) ceramics were fabricated. The influence of co-doping of NN and high entropy perovskite oxide (SZSHTN) on the phase structure, microstructure and dielectric properties of NBT-based lead-free ceramics was investigated. Dense microstructure with a grain size of∼5μm is observed. Whenx = 0.25, a wide dielectric temperature stable range of − 35.4–224.3∘C with a low temperature coefficient of capacitance of< 10% is achieved, fulfilling the industry standard of Y9P specification. Furthermore, excellent energy storage performance with recoverable energy density of 2.4 J/cm³, discharge efficiency of 71%, power density of 25.495 MW/cm³ and discharge rate< 200 ns are simultaneously obtained, which shows great potential for high temperature capacitor applications.