 Toward the realization of reliable Li-ion batteries with high performance and safety, component materials such as those of the current collector and negative electrode require further innovation. Sn, one of the most promising negative-electrode materials, can be electrochemically fixed on a substrate without any binder or conductive additive. However, the pulverization of Sn-plated films on substrates caused by large volume changes during Li–Sn reactions is the main reason hindering the practical application of Sn-plated electrodes. In the present study, we developed an electrodeposited three-dimensional (3D) Cu substrate applied to underlayer of the electrode. The effect of substrate geometry on the charge–discharge performance of the Sn electrode was investigated. The 3D-Cu/Sn electrode exhibited superior cycling performance with a reversible capacity of 470 mA h g−1 even at the 300th cycle, whereas the Sn-plated electrode prepared on a typical flat Cu substrate showed a capacity of only 20 mA h g−1. The results demonstrated that the 3D structure played a key role in accommodating volumetric changes in the Sn to suppress electrode disintegration. The developed 3D-Cu substrate will be significantly useful as a current collector for alloy-based active materials.