The influence of the surface and small-scale effects on electromechanical coupling behavior of a piezoelectric nanowire is studied by using the beam bending model. An explicit formula for the electromechanical coupling (EMC) coefficient of the piezoelectric nanowire is obtained based on the nonlocal electroelasticity theory. It is found that the inclusion of the nonlocal effect in the model produces a significant difference from the past model which ignores the nonlocal effect in the prediction of the EMC coefficient and the electric field in the nanowire, confirming the significance of including the surface and small-scale effects in the analysis of piezoelectric nanowires. In particular, the influence of surface effects on the electric field is dominant for smaller nonlocal parameters. If the nanowire is subjected to an applied concentrated load and without surface effect, the nonlocal effect has no effect on its bending and electric field. This study might be helpful for understanding the size-dependent electromechanical properties of piezoelectric nanowires and design of piezoelectric-beam–based nanogenerators.