Nanostructured Fe₃O₄/C composites are very attractive for high-performance magnetic targeted drug carriers. Herein, Fe₃O₄/C composite nanospheres with good dispersity are prepared by a simple one-step hydrothermal synthesis and subsequent heat treatment in Ar. The composite nanospheres consist of clustered primary nanoparticles, and exhibit a hierarchical architecture with a high specific surface area of 119.3 m² g-1. The Fe₃O₄/C composite nanospheres show a high saturation magnetization value of 101 emu g-1 and good biocompatibility. In particular, the composite nanospheres deliver a large loading content (85.8%) of epirubicin hydrochloride (EPI), resulting from their unique composition and microstructure. More importantly, the release of EPI from the EPI-loaded magnetic carrier (Fe₃O₄/C-EPI) may be enhanced by both a slightly acidic environment and a rotating magnetic field induced by a simple motor-driven magnet system. The above favorable properties make the hierarchical Fe₃O₄/C composite sample a promising candidate for magnetic targeting nanocarriers of EPI.