A keypad printed circuit board (PCB) assembly for a mobile phone integrated with a light guide plate providing a light-emitting function using a light emitting diode (LED) and the light guide plate is provided. The keypad PCB assembly includes a PCB on which a plurality of light emitting diodes (LEDs) is surface-mounted such that they are able to emit light from a side of the PCB, a metal dome section including metal dome parts attached to positions corresponding to signal contacts of the PCB, and a dome tape covering a gap between the metal dome parts excluding a portion overlapped with the LEDs, and a light guide plate coupled to an upper portion of the metal dome section so that the light guide plate and the metal dome section are integrated into one piece, leaving the space therebetween, and having thereunder an uneven pattern reflecting light incident from the LEDs, an LED cover provided on a position corresponding to the LEDs, and a circumferential light-shielding part filling the end-side space between the light guide plate and the metal dome section.