Ternary Ni–Co–Se/carbon nanotube nanocomposites have been successfully prepared via a one-step hydrothermal strategy. When used as electrode materials for lithium-ion batteries, the Ni–Co–Se/CNT composite exhibits good lithium storage performances including excellent cycling stability and outstanding specific capacity, good cycling stability, and high initial coulombic efficiency. A high specific capacity of 687.8 mA h g⁻¹ after 100 charge–discharge cycles at a current density of 0.5 A g⁻¹ with high cycling stability is achieved. The excellent battery performance of Ni–Co–Se/CNT should be attributed to the synergistic effect of Ni and Co ions and the formed network structure.