Green and facile process for Ni0.4Cu0.2Zn0.4Fe2-xEuxO4 (x = 0.00-0.10) spinel ferrite nanoparticles (SNPs) prepared via ultrasonic irradiation (without any post annealing process) has been deeply investigated. The influence of Eu3+ substitutions on the structure, morphological, optical, magnetic, electrical and dielectric traits of NiCuZn SNPs was assessed. Tauc plots revealed direct optical band gaps in a very tight interval of 1.86-1.90 eV. Magnetization measurements exposed a superparamagnetic behavior at room temperature and below the blocking temperature (T-B) a superparamagnetic-ferromagnetic transition was noticed. The saturation magnetization (M-s) value is highest for pure Ni0.4Cu0.2Zn0.4Fe2O4 (i.e. x = 0.00) SNP with M-s similar to 58.9 emu/g at room temperature. The saturation magnetization (M-s) declines with rising Eu3+ substituting content. AC conductivity decreases as a function of exponent power base law. Maximum variation in dc conductivity is observed to be around the substitution ratio of x = 0.02. It is found that activation energy is highly dependent on both Eu ions substitution ratios and temperature ranges. The frequency dependence of dielectric functions is explained by Koop's models based on Maxwell-Wagner theory.