A facile strategy to prepare MoS2–MoO3 hybrid nanomaterials is developed, based on the heat-assisted partial oxidation of lithium-exfoliated MoS2 nanosheets in air followed by thermal-annealing-driven crystallization. The obtained MoS2–MoO3 hybrid nanomaterial exhibits p-type conductivity. As a proof-of-concept application, an n-type SiC/p-type MoS2–MoO3 heterojunction is used as the active layer for light-emitting diodes. The origins of the electroluminescence from the device are theoretically investigated. This facile synthesis and application of hybrid nanomaterials opens up avenues to develop new advanced materials for various functional applications, such as in electrics, optoelectronics, clean energy, and information storage.