New NiSn(OH)6hexahydroxide nanoparticles were synthesised through a co-precipitation method using various concentrations of Ni2+and Sn4+ions (e.g., 1:0, 0:1, 1:2, 1:1, and 2:1; namely, N, S, NS-3, NS-2, and NS-1) with an ammonia solution. The perovskite NiSn(OH)6was confirmed from powder X-ray diffraction and molecule interactions due to different binding environments of Ni, Sn, O, and water molecules observed from an FT-IR analysis. An electronic transition was detected from tin (Sn 3d) and nickel (Ni 2p) to oxygen (O 2p) from UV-Vis/IR spectroscopy. Photo luminescence spectroscopy (PL) identified that the emission observed at 400–800 nm in the visible region was caused by oxygen vacancies due to various oxidation states of Ni and Sn metals. A spherical nanoparticle morphology was observed from FE-SEM; this was due to the combination of Ni2+and Sn4+increasing the size and porosity of the nanoparticle. The elemental (Ni and Sn) distribution and binding energy of the nanoparticle were confirmed by EDAX and XPS analyses. Among the prepared various nanoparticles, NS-2 showed a maximum specific capacitance of 607 Fg−1at 1 Ag−1and 56% capacitance retention (338 Fg−1and 5 Ag−1), even when increasing the current density five times, and excellent cycle stability due to combining Ni2+with Sn4+, which improved the ionic and electrical conductivity. EIS provided evidence for NS-2’s low charge transfer resistance compared with other prepared samples. Moreover, the NS-2//AC (activated carbon) asymmetric supercapacitor exhibited the highest energy density and high-power density along with excellent cycle stability, making it the ideal material for real-time applications.