FeOF/reduced graphene oxide (r-GO) nanocomposites are synthesized with approximately 8 and 13 wt% r-GO. The FeOF nanoparticles are fabricated using FeSiF6⋅6H2O as a precursor through solvothermal treatment with 1-propanol. This method provides a more reliable and facile wet-chemical route to synthesize phase-pure FeOF without FeF2 and Fe2O3 impurities, as compared to the annealing process in air. The FeF2 phase is formed as an intermediate during the synthetic process. The prepared FeOF/r-GO sample with 13 wt% r-GO (FeG20) exhibits improved discharge capacity, cycling stability, and rate performance as a cathode material in sodium-ion batteries, compared to the bare FeOF at 1.2–4.0 V. The enhanced electrochemical properties for sodium-ion storage are mainly attributed to the size-controlled FeOF nanoparticles and their intimate contact with the conductive r-GO matrix.