Transition metal oxides (TMOs) have drawn great attention in applications towards negative electrodes for lithium-ion batteries (LIBs). TMOs undergo conversion reactions upon discharge/charge process, which involves volume changes that cause pulverization and further result in poor cycling performances. Thus, it is important to engineer the microstructure of TMOs to accommodate the volume expansion/contraction during discharge/charge process and to improve the charge-transfer process. Herein, we report nanostructured CuO nanoflake arrays with a highly open microstructure on a nanoporous Cu substrate as binder-free negative electordes for LIBs. Nanoporous Cu substrate was obtained by dealloying process. By oxidizing one single side of a nanoporous Cu substrate under mild conditions, the 2D self-supported CuO nanoflake arrays were fabricated and can provide fast ion diffusion paths and accommodate large volume changes in the process of discharge/charge. Due to the synergistic effects of the highly conductive substrate and the intrinsically stable microstructure, the as-prepared CuO electrodes deliver a high capacity with stable performance of ∼100% capacity retention (∼800 mAh·g−1) after 120 cycles, and good rate performances up to 10 C. Considering the enhanced charge-transfer process, notable structural stability, and low-cost fabrication, the as-prepared CuO negative electrodes hold great promise for advanced LIBs.