Barium titanate doped yttrium ceramics with different grain sizes were prepared by a solid-state method at three different sintering temperatures. The SEM micrograph observation revealed well-developed grain morphology and a dense, homogeneous microstructure in the Ba0.98Y0.02Ti0.995O3 ceramics. However, an increase in pores was observed at 1300 °C, affecting the dielectric characteristics. Additionally, at 1350 °C, there was a significant increase in the average grain size to approximately 3.508 µm. The permittivity and conductivity were found to be strongly dependent on the grain sizes; They increased with increasing the grain size down to 1.530 μm on average and then decreased. The grain size-dependent conductivity might be explained by the effect of grain boundary on charge carrier transport. The grain size of the ceramics with the highest permittivity of 1700 was approximately 1.530 μm.