Silicon (Si) possesses high theoretical lithium-ion (Li+)-storage capability but is still limited to a huge volume change in the charging-discharging process and has poor conductivity, which hinders its application. Here, the authors report a novel three-dimensional (3D) continuous porous silicon/copper (Cu) composite film through non-solvent-induced phase separation and heat treatment. The composite film inherits the developed 3D channels of copper with a proper pore size (1-5 μm), while the silicon particles can evenly adhere onto the 3D copper current collector tightly by heat treatment. It provides a reversible capacity of up to 2054.9 mAh/g after 150 cycles under a current of 0.05 C and exhibits a good rate capability (609.9 mAh/g at a high rate of 1 C) when used as an electrode. Naturally, the 3D porous architecture could not only shorten the electron/ion transmission path but also induce space-confined silicon, which provides a stable space for the volume expansion/contraction of silicon to restrict pulverization. This strategy provides ideas for the development of high-energy-density electrodes for next-generation energy-storage systems.