We demonstrate a low-temperature fabricated MEMS-based piezoelectric ultrasonic energy harvester with enhanced device performance. Compared to state-of-the-art, our work uses a low-temperature bonding method, which ensures the integrated piezoelectric material undergoes prominently lower temperatures (≤ 85 °C) throughout the whole fabrication process. Due to this, bulk PZT-5H, a material with superior piezoelectric properties, could be used in this type of application for the first time. The method guarantees the device fabrication temperature well below the PZT-5H Curie temperature (225 °C) and preserves its piezoelectricity to the greatest extent. As a result, devices fabricated using the proposed method achieve higher performance than the devices prepared by the MEMS fabrication method using BCB bonding. The root-mean-square voltage and the average power outputs at the frequency (170 kHz) where maximum voltage and power outputs were observed were improved by 38 % and 92 %, respectively.