We report an efficient hole transporting layer (HTL) for organic solar cell (OSC) based on solution-processed organic-inorganic hybrid composed of ultrasonic-exfoliated MoS2 nanosheets and dopamine-copolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) derivative (DA-P). The OSCs based on this new hybrid HTL show a marked performance improvement over those with single-component HTLs, and they retain up to 80% of their original power conversion efficiency after 35 days. Our investigations reveal that the boost in performance is due to a synergistic effect that improves both hole transport and extraction ability. This effect is mainly due to the doping of exfoliated-MoS2 nanosheets on DA-P. We employ a comprehensive range of spectroscopies to uncover that the dopant is derived from the oxidation products of MoS2 nanosheets during the ultrasonic exfoliation. Our work demonstrates an efficient hybrid HTL and offers new insights into the interaction of exfoliated-MoS2 nanosheets and the PEDOT derivatives.