Two-dimensional (2D) semiconductor devices hold great promise in specialized operating regimes including radio-frequency, high-temperature, and cryogenic conditions—yet their potential for power handling has received little emphasis, so far. Here we report a molybdenum disulphide (MoS₂) device design that strategically selects the channel width (W) and length (L) to distribute current density and mitigate self-heating, enabling operation at a source-drain bias V_ds of 10 V and a drain current I_ds of 0.1 A, while maintaining an on/off ratio of 10⁵. This corresponds to sustained dissipation P = I_dsV_ds ~ 1 W, and highlights a pathway for Watt-level switching in van der Waals electronics. We demonstrate a sensor circuit that uses our Watt-level MoS₂ transistors to function as a step-down converter and a switching device. Further, a proof-of-concept on flexible substrates is presented. Our findings mark a step change in 2D power electronics, paving the way for higher-voltage devices compatible with flexible substrates and, ultimately, wearable and conformal power systems.