Piezoelectric actuation micro-/nanopositioning systems have been widely employed in diverse micro-/nanomanipulation applications. This paper presents the design, analysis, and validation of a new control scheme termed input-output-based digital sliding-mode control (IODSMC) to suppress the unmolded nonlinearity and disturbance in piezoelectric micro-/nanopositioning systems. The controller is established based on a linear digital input-output nominal model. The scheme facilitates a rapid implementation because the construction of either a hysteresis model or a state observer is not needed. The chattering-free control is capable of achieving an O(T^{2}) output tracking accuracy by overcoming the model disturbance. Moreover, the stability of the control system is proved, and its effectiveness is validated through experimental investigations on a piezo-driven micropositioning system. Results demonstrate that the IODSMC scheme is superior to the conventional proportional-integral-derivative control for motion-tracking tasks. Furthermore, it exhibits promising robustness in front of internal and external disturbances. © 1982-2012 IEEE.