An electronic device and a knob module thereof are provided. The knob module includes a circuit board, a rotary encoder, a light guide structure, a plurality of light emitting units, and a rotation cover. The rotary encoder is disposed on the circuit board. The light guide structure is disposed on the circuit board. The light guide structure includes a light guide ring and an annular light guide wall. The light guide ring surrounds the rotary encoder. The annular light guide wall extends downward from the light guide ring to abut against the circuit board. The plurality of light emitting units is disposed on the circuit board and located between the annular light guide wall and the rotary encoder for emitting light toward the annular light guide wall. The rotation cover is disposed on the rotary encoder.