Electromechanical ceramics, owing to their large electrostrain and low hysteresis, have emerged as promising approaches for advancing high-precision transducer applications. Although tremendous efforts have been made to synthesize colossal, crack-free ceramics, this remains a key challenge. To address this issue, we developed a facile, time-efficient, and humidity-assisted method to synthesize a series of lead-free ceramics, including BaTiO₃, (Ba,Sr)TiO₃, Ba(Zr,Ti)O₃, (Bi,Na)TiO₃, and (K,Na)NbO₃. Their microstructures, as well as their dielectric and ferroelectric properties, were subsequently investigated. Our analysis revealed that humidity not only lowers the drying temperature to as low as 20 °C but also significantly reduces the processing time, allowing for the fabrication of monolithic ceramics as large as 10 cm × 10 cm. Additionally, a tunable dielectric constant ranging from 489.3 to 4215.7 can be achieved simply by adjusting the porosity. Moreover, these electromechanical ceramics exhibit excellent electrostrictive performance under an AC bias, with a strain of ~0.46%, corresponding to an electrostrictive coefficient of 125 nm²∙V⁻². Our work offers a scalable and cost-effective strategy to achieve wafer-scale crack-free ceramics, thereby providing a new opportunity for the development of actuators, sensors, motors, and transducers.