This study introduces a unique method for the production of a highly sensitive tennis racket-shaped optical fiber humidity sensor consisting of a U-shaped probe and electrospun functional nanofibers. Functional nanofibers of the racket consist of conjugated polymers prepared through a mixture of two kinds of polymer molecules electrospun in an electric field of about 1.7 kV/cm. Interpenetrating polymer networks were fabricated through electrospinning, for which a polymer solution of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) doped in polyvinyl alcohol (PVA) was used. The hydrogen-bonding interaction of the interpenetrating polymer networks/H2O plays a major role in increasing the sensitivity of the humidity sensor. The sensitivity of the sensor was found to be -0.990 nm/%RH, which was 16.02 % greater than that of undoped PEDOT:PSS PVA nanofibers.