Bi4Ti3−2xNbxTax−ySbyO12 (BTNTS) ceramics were investigated as a potential candidate of lead-free piezoelectric ceramics. X-ray diffraction results indicated that all samples have monoclinic structure. Scanning electron microscopic studies revealed that the addition of Sb2O3 did not cause a suppressed grain growth for their morphological behavior. The Bi4Ti2.98Nb0.01Ta0.002Sb0.008O12 (8BTNTS) ceramics possess a dielectric constant of 1328 at 100 kHz, a piezoelectric constant (d33) of 35 pC/N and Curie temperature (Tc) of 664°C. The electrical properties of the investigated compositions exhibited a significant dependence on the content of Sb2O3 addition. The electrical conductivity for 8BTNTS ceramics was lower than that of other investigated compositions. Dielectric and electrical transport properties have been carried out over a wide range of frequency and temperature in order to explore the conduction mechanism in the investigated samples. The activation energy associated with the electrical relaxation determined from the electric modulus spectra was found to be 1.0±0.03 eV, close to that of the activation energy for DC conductivity (1.08±0.02 eV). It suggests that the movements of oxygen ions are responsible for both the ionic conduction as well as relaxation process.