<p>This paper investigates the size-dependent elastohydrodynamic lubrication (EHL) contact of a transversely isotropic piezoelectric half-plane under a rigid insulating or conducting cylindrical punch based on the couple-stress theory. In the contact area, the electric potential of the punch is constant when it is considered as a perfect conductor. The size effect connected with the material’s microstructure is characterized by the characteristic material length. The lubricant at the contact surface, whose density and viscosity depend on fluid pressure, is assumed to be a non-Newtonian fluid. To obtain the film thickness and fluid pressure, the fluid–solid coupled nonlinear equations are solved by an iterative method. The influences of piezoelectric effect, conductivity of punch, size parameter, slide/roll ratio, Eyring stress of non-Newtonian fluid, total electric charge, fluid viscosity, and entraining velocity on the size-dependent EHL contact behavior are analyzed. This investigation provides theoretical assistance for improving the electro-mechanical wear and contact damage of microscale piezoelectric devices.</p>