A keypad panel assembly having a laterally-illuminated keypad surface is arranged on an electronic device. The keypad panel includes a light-guiding plate and a panel. The light-guiding plate has a carrier thereon. One side surface of the carrier is provided with a plurality of protruding strips. Each protruding strip is provided with a plurality of light-guiding particles at positions corresponding to the other side surface of the carrier. The top surface of the protruding strip is provided with a reflective layer. The panel is arranged on one side surface of the carrier, and is provided thereon with a plurality of rectangular keypads. One side surface of each keypad is provided with an icon, and a plurality of hollowed portions is provided between each keypad and the panel. Each hollowed portion encloses a rectangular shape and corresponds to the protruding strip of the carrier. After the protruding strip passes through the hollowed portion, the height of the protruding strip is larger than those of the keypad and the icon. After the light generated by a backlight source of the electronic device is introduced from one side of the light-guiding plate, the light-guiding particles focus the light on the protruding strip. Then, the light illuminates the keypad surface from both sides of the protruding strip, so that a user can see the icon displayed on the keypad surface clearly.