The study investigates the effects of ultrafast high-temperature sintering (UHS) on the microstructure and properties of 3 mol% Y2O3 stabilized ZrO2 (3YSZ). UHS, a rapid sintering technique, allows for ultra-rapid consolidation of YSZ nanopowders (<30 seconds) with a significant reduction in grain size (over 60% reduction at a fixed density level) compared to conventional sintering. The electric field applied during sintering had a minor impact on the microstructure and properties. UHS did not affect the hardness and electrochemical properties of the sintered bodies. The results show that UHS can achieve efficient and homogeneous densification, reducing the processing temperature by more than 200 °C compared to conventional heating. The microstructure of UHS-sintered 3YSZ is characterized by finer grains and smaller, lower-coordinated pores, which contribute to the accelerated consolidation. However, the macroscopic properties, such as hardness and electrochemical behavior, are similar to those obtained through conventional sintering. The study concludes that the enhanced properties observed in flash sintering techniques may not be universally applicable to all rapid sintering methods.The study investigates the effects of ultrafast high-temperature sintering (UHS) on the microstructure and properties of 3 mol% Y2O3 stabilized ZrO2 (3YSZ). UHS, a rapid sintering technique, allows for ultra-rapid consolidation of YSZ nanopowders (<30 seconds) with a significant reduction in grain size (over 60% reduction at a fixed density level) compared to conventional sintering. The electric field applied during sintering had a minor impact on the microstructure and properties. UHS did not affect the hardness and electrochemical properties of the sintered bodies. The results show that UHS can achieve efficient and homogeneous densification, reducing the processing temperature by more than 200 °C compared to conventional heating. The microstructure of UHS-sintered 3YSZ is characterized by finer grains and smaller, lower-coordinated pores, which contribute to the accelerated consolidation. However, the macroscopic properties, such as hardness and electrochemical behavior, are similar to those obtained through conventional sintering. The study concludes that the enhanced properties observed in flash sintering techniques may not be universally applicable to all rapid sintering methods.