A quantum dot device including a first electrode and a second electrode each having a surface opposite the other, a quantum dot layer disposed between the first electrode and the second electrode, and an electron auxiliary layer disposed between the quantum dot layer and the second electrode, wherein the electron auxiliary layer includes inorganic nanoparticles including an alkaline-earth metal, and an alkali metal, an alkali metal compound, or a combination thereof, and an electronic device including the quantum dot device.