A study is conducted to demonstrate fast and reversible actuation of metallic muscles composed of nickel nanowire-forest. The synthesis approach creates a mechanically strong 3D network with overall dimensions of centimeters. Energy dispersive X-ray spectroscopy shows that Ni is the dominate element within the bilayered Ni, with a slight amount of Co possibly due to the impurity of the electrodeposition solution, and O due to the formation of a passive film Ni(OH)2 on the Ni surface when template was selectively removed by 1 M NaOH solution. The electrochemical actuation has been characterized by an in situ experimental setup.