A two-dimensional material plasmonic laser (device) is provided with a surface plasmonic cavity and an atomically thin semiconductor monolayer gain medium disposed on the surface plasmonic cavity. Under optical pumping or electrical pumping, the surface plasmonic cavity provides a laser feedback mechanism by coupling electron-hole pairs confined in the atomically thin semiconductor monolayer gain medium and the surface plasmon modes in the dark-mode surface plasmonic cavity, and a laser light is emitted from the two-dimensional material plasmonic laser.