Atomically thin transition metal dichalcogenides (TMDCs) are an emerging class of two-dimensional semiconductors. Recently, the first optoelectronic devices featuring photodetection as well as electroluminescence have been demonstrated using monolayer TMDCs as active material. However, the light−matter coupling for atomically thin TMDCs is limited by their small absorption length and low photoluminescence quantum yield. Here, we significantly increase the light−matter interaction in monolayer tungsten disulfide (WS 2 ) by coupling the atomically thin semiconductor to a plasmonic nanoantenna. Due to the plasmon resonance of the nanoantenna, strongly enhanced optical near-fields are generated within the WS 2 monolayer. We observe an increase in photoluminescence intensity by more than 1 order of magnitude, resulting from a combined absorption and emission enhancement of the exciton in the WS 2 monolayer. The polarization characteristics of the coupled system are governed by the nanoantenna. The robust nanoantenna−monolayer hybrid paves the way for efficient photodetectors, solar cells, and light-emitting devices based on two-dimensional materials.