Uniform and porous ultrathin-carbon-coated pyrite (FeS₂@C) nanooctahedra have been fabricated via a facile solvothermal method with subsequent carbon-coating-annealing and acid-pickling steps. Benefitting from their high conductivity, short Na⁺ diffusion distance, large surface area, and robust structure stability, the FeS₂@C electrodes delivered a high specific capacity, excellent rate capability and superiorly stable cycling performance, suggesting a potential application in advanced sodium ion batteries.