Self-assembled FeO hierarchical microspheres (HMSs) were prepared by a one-pot synchronous reduction-self-assembling (SRSA) hydrothermal method. In this simple and inexpensive synthetic process, only glycerol, water, and a single iron source (potassium ferricyanide (K[Fe(CN)])) were employed as reactants without additional reductants, surfactants, or additives. The iron source, K[Fe(CN)], and glycerol significantly affected the synthesis of FeO HMSs. FeO HMSs with a self-assembled spherical shape readily functioned as high-performance anode materials for lithiumion batteries with a specific capacity of > 1000 mA h g at 0.5 A g after 270 cycles. Further charging and discharging results revealed that FeO HMSs displayed good reversible performance (> 1000 mA h g) and cycling stability (700 cycles) at 0.5 A g. Furthermore, as multifunctional materials, the as obtained FeO HMSs also exhibited high saturation magnetization (99.5 emu g) at room temperature (25°C) and could be further employed as efficient and magnetically recyclable catalysts for the hydrogenation of nitro compounds.