In this work, a microwave approach is developed to rapidly synthesize ultralong zinc pyrovanadate (Zn3V2O7(OH)2·2H2O, ZVO) nanowires with a porous crystal framework. It is shown that our synthesis strategy can easily be extended to fabricate other metal pyrovanadate compounds. The zinc pyrovanadate nanowires show significantly improved electrochemical performance when used as intercalation cathode for aqueous zinc–ion battery. Specifically, the ZVO cathode delivers high capacities of 213 and 76 mA h g−1 at current densities of 50 and 3000 mA g−1, respectively. Furthermore, the Zn//ZVO cells show good cycling stability up to 300 cycles. The estimated energy density of this Zn cell is ≈214Wh kg−1, which is much higher than commercial lead–acid batteries. Significant insight into the Zn-storage mechanism in the pyrovanadate cathodes is presented using multiple analytical methods. In addition, it is shown that our prototype device can power a 1.5 V temperature sensor for at least 24 h.