We demonstrate the fabrication of freestanding and flexible MnO-decorated carbon nanofiber (CNF) composites as lithium-ion battery anode materials. They showed an initial capacity of 1131mAh·g−1 and a retention capacity of 923mAh·g−1 after 90 charge-discharge cycles under a current rate of 123mA·g−1. Decoration of MnO nanocrystals on the CNFs enhanced the lithium storage capacity of the composites. The optimal concentration of MnO was identified by varying its weight percentage from 0 to 7%. When the concentration was increased, more reaction sites for lithium ions were formed, which in turn increased the overall specific capacity. The intensity of the D band in the Raman spectra of the decorated CNFs was higher than that of the G band, indicating the enhanced diffusion of lithium ions. The plateau region of the discharge curve observed in the cases of higher MnO concentrations indicated the active reduction of MnO; consequently, a higher reversible capacity was achieved. These flexible and freestanding MnO-CNF nanocomposites can be used in lightweight, portable, and flexible batteries.