In2O3 uniformly modified MoS2 (In2O3/MoS2) nanoflowers were synthesized via a green, efficient, and controllable normal-pressure microwave-assisted route and a subsequent calcination process, using MoS2 nanoflowers as substrates. The In2O3/MoS2 nanoflower is composed of extremely thin MoS2 nanosheets, among which In2O3 nanoparticles are uniformly attached to the MoS2 nanosheets. Numerous p–n heterojunctions and oxygen vacancies are present on the surfaces of the In2O3/MoS2 nanoflowers. The In2O3/MoS2 composites exhibited high sensitivity and selectivity, along with rapid response and recovery to methanol vapor at 240 °C. The In2O3/MoS2 nanoflower sensors exhibit rapid response and recovery rates toward methanol, particularly notable with a recovery time of only 15 s for 100 ppm methanol. The In2O3/MoS2 sensors also demonstrate excellent stability and reproducibility, with a remarkable selectivity toward methanol. This research presents a promising approach for the future design and preparation of In2O3/MoS2 composite for methanol detection.