MoO3 is a promising anode material for energy storage, but its electrochemical performance is still unsatisfactory. Herein, α-MoO3 nanosheets vertically grown on activated carbon fiber cloth as superior anode materials for Li- and Na-ion batteries were achieved by the method of controlled preparation. For Li-ion batteries, the resulting MoO3 array electrodes exhibit a high discharge capacity of 4.48 mA h cm-2 (1780 mA h g-1) at 0.1 mA cm-2 and outstanding cycling stability at 0.5 mA cm-2 (94% capacity retention after 200 cycles). Moreover, for Na-ion batteries, they also show an excellent electrochemical performance with a discharge capacity of 2.5 mA h cm-2 (1621 mA h g-1) at 0.1 mA cm-2 and capacity retention of 90% after 200 cycles at 0.2 mA cm-2. This study suggests that MoO3 array electrodes can be hopefully used as promising anode materials for energy storage applications.