A keyswitch backlight structure includes a light-guiding layer, a reflective layer, and a transparent adhesive layer. The light-guiding layer has a bottom surface, a light-emitting surface opposite to the bottom surface, and a surface microstructure formed on the light-emitting surface. The reflective layer is disposed opposite to the bottom surface. The transparent adhesive layer is closely attached to and between the reflective layer and the light-guiding layer corresponding to the surface microstructure. An illuminated keyswitch structure includes base plate, a keycap, a supporting mechanism, and the above keyswitch backlight structure. The keyswitch backlight structure and the base plate are stacked. The supporting mechanism is connected to and between the base plate and the keycap for lifting the keycap relative to the base plate. Light entering the light-guiding layer exits the light-guiding layer through the light-emitting surface to illuminate a transparent indication area of the keycap.