The concept of a self-powered water desalination device with the capability of simultaneous electricity generation is introduced. The as-fabricated metal-air desalination battery takes the advantage of integration of ion selective membranes with an aluminum-air battery in a three-chamber cell. The maximum power density of 2.83 W m−2 at 6.58 A.m−2 current density and 0.43 V output voltage is obtained using natural saltwater as the electrolyte. The as-fabricated device decreases the salinity of Caspian saltwater by 37.8% with 10 mW h energy generation in 14-h operation. The obtained results are promising to present considerable room for improvement of the as-fabricated device.