Exciton emitters in two-dimensional monolayer transition-metal dichalcogenides (TMDs) provide a boulevard for the emerging optoelectronic field, ranging from miniaturized light-emitting diodes to quantum emitters and optical communications. However, the low quantum efficiency from limited light-matter interactions and harmful substrate effects seriously hinders their applications. In this work, we achieve a ∼438-fold exciton photoluminescence enhancement by constructing a Fabry-Pérot cavity consisting of monolayer WS