Nanostructured transition metal oxides are considered as some of the promising anode materials for rapidly emerging sodium ion batteries. Herein, a hierarchically porous CoNiO₂ nanosheet array film is prepared via a low-temperature solvothermal method with subsequent annealing treatment. As a self-supported anode for sodium ion batteries (SIBs), the as-prepared hierarchically porous CoNiO₂ nanosheet array film manifests superior sodium storage performance. The film electrode delivers a large reversible capacity of 746.6 mA h g⁻¹ after 100 cycles at 200 mA g⁻¹. In particular, a capacity of 419 mA h g⁻¹ is achieved at a high current density of 1600 mA g⁻¹, demonstrating a good rate capability.