Complex multilayer stacks based on metal-dielectric (cermet) or metal nitrides and borides are widely explored for solar energy harvesting. Inevitably, complicated multi-target co-sputtering process and expensive material costs are required. To address this issue, herein, we demonstrate that Mo nanoparticles spontaneously embedded in amorphous MoOx matrix (Mo@MoOx), facilely achieved by one- step limited reactive sputtering approach with a very low oxygen/argon ratio using only a single Mo target, possess excellent optical absorption. The developed Mo@MoOx absorber film exhibits a superior solar absorptivity of 0.91, a low thermal emissivity of 0.06, as well as a remarkable long-term thermal stability of up to 450 degrees C in vacuum, which is the equivalent photo-thermal performance compared to the multilayer absorbers. These findings deliver a new insight into pathway for designing simple, efficient but feasible absorber in large-scale industrial processing.