An electrically controlled viewing angle switching device including a first electrode, a second electrode, a liquid crystal layer, multiple dye molecules, and a polarizer is provided. The second electrode is disposed opposite to the first electrode. The liquid crystal layer is disposed between the first electrode and the second electrode and has an optical axis. The dye molecules are dispersedly disposed in the liquid crystal layer. Each of the dye molecules is arranged corresponding to the optical axis of the liquid crystal layer. The polarizer is stacked on the liquid crystal layer. The axial direction of the optical axis of the liquid crystal layer is perpendicular to the axial direction of the transmission axis of the polarizer. A display device using the electrically controlled viewing angle switching device is also provided.