A novel nanocomposite of graphene–encapsulated selenium/polyaniline core–shell nanowires (G@Se/PANI) has been designed and synthesized under the condition of low temperature without heating and investigated as a cathode material for Li-ion batteries. In this nanocomposite, selenium nanowires are well-sealed in the PANI layer with a thickness of ≈25nm forming a core/shell structure and then the Se/PANI core–shell nanowires are uniformly encapsulated in the graphene nanosheets. As expected, the G@Se/PANI nanocomposite exhibits enhanced cycling performance and high-rate capability. The G@Se/PANI nanocomposite displays a reversible discharge capacity of 567.1mAh/g at 0.2C after 200th cycle and 510.9mAh/g at 2C, which could be associated with the highly electrical conductivity of graphene sheets and the unique PANI shell, together with the one-dimensional structure of selenium in the G@Se/PANI nanocomposite.