Grain-size effect on functional properties of piezoceramics is nowadays an important topic due to the potential applications of these materials at the submicron scale. In this context, we explore the effect of the grain size reduction on the functional properties stability of piezoceramics. Submicron- and micro-structured Pb(Zr,Ti)O3-based materials are taken as model samples to carry out this study. Rayleigh analysis is used to quantitatively evaluate the domain wall contribution. The results show that the stability of properties depends strongly on grain size. Specifically, the nonlinear response decreases significantly when the grain size is reduced to the submicron scale. This behavior can be explained by taking into account that a grain size reduction involves a grain boundary increment, which may clamp domain walls. The results suggest that grain size engineering may be an effective alternative to the widely used compositional engineering in order to control the undesirable nonlinear behavior in piezoceramics.