<p>In this study, the problem of determining the length scale parameter and the transverse piezoelectric coefficient is addressed using an inverse identification method. This method is proposed as an alternative to traditional experimental techniques. Unlike conventional experimental methods, where the length scale parameter and the piezoelectric coefficient are calculated separately, both parameters are simultaneously estimated in the present work. The inverse approach provides an efficient and cost-effective approach for determining these key parameters, significantly reducing the high costs associated with traditional experimental techniques. First, a size-dependent mathematical model is proposed based on the modified couple stress theory, in which the microplate is modeled using the Kirchhoff plate theory. Additionally, Von Kármán nonlinear strains are incorporated into the mathematical model to account for geometric nonlinearities. Due to the substantial impact of the length scale parameter on mechanical behavior and the critical role of the transverse piezoelectric coefficient, accurate and affordable determination of these parameters is essential. Consequently, an inverse problem is defined, and a robust solution technique is developed. Finally, a thorough investigation is conducted to examine the influence of initial guesses and measurement errors on the accuracy and robustness of the proposed identification method.</p>