This study reports the sintering of Mg$_{0.8}$Zn$_{0.2}$TiO$_3$ (MZT) with an addition of K$_{0.5}$Na$_{0.5}$VO$_3$ (KNV) and Bi$_2$O$_3$. The sintering temperature was performed at 950°C for 4 h and attained a maximum relative density of 97.71% in a composition of 85% mol MZT–10% mol KNV–5% Bi$_2$O$_3$ (MZT85). Structure, microstructure and phase present in the sample were analysed using X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. MgZnTiO$_3$, KNaVO$_3$ and BiVO$_4$ were found, besides, the non-crystalline phase was also detected and supposed to be the Bi$_2$O$_3$ melted amorphous phase. Furthermore, with an increase of the lattice parameter and cell volume of samples, it was believed that the sintering aid dissolved partially in the MZT matrix. The electrical properties characterization discovered that at low frequencies (1 Hz–32 MHz) a broader range of space charge polarization was observed, meanwhile, at high frequency (X-band) an enhancement of the permittivity and quality factor Qxf. The relative permittivity ${\varepsilon}_r$ ${\approx}$16.08, the dielectric loss (tan ${\delta}$) ${\sim}$10$^{-2}$ and Qxf = 11.386 GHz at 10 GHz for the MZT85 sample was observed.