Surface-charge-induced reversible and millimeter-scale deflection is found in a bilayered Ni cantilever upon cyclic potential triggering. The nanowire-forest structure, in which unidirectional primary nanowires are evenly separated by crosslinking subnanowires, ensures fast ion transport leading to a record-high strain response time approximate to 0.1 s. The actuation is sustainable beyond 800 cycles; the strain energy is compatible with human skeletal muscles.