<p>A multi-state transistor that converts optical inputs into discrete logic outputs provides a device-level framework for optoelectronic computing beyond the binary paradigm. Here, we present a light-driven ternary heterojunction transistor (T-HTR), featuring three distinct states – off, on, and a light-tunable intermediate state – within a single device. The multi-state switching is achieved by a p-type/n-type heterojunction with a controlled charge injection barrier at the source electrode. This design enables the device to be maintained in the off-state in the absence of intermediate logic operations, thereby minimizing static power consumption. An optoelectronic ternary logic inverter based on the T-HTR is capable of full-swing pull-up and pull-down operations with a light-tunable intermediate state, realizing the functions of standard, positive, and negative ternary inverters within a single device. We further demonstrate a pixel-level sensory circuit as a proof-of-concept for in-sensor computing, enabling multifunctional image processing tasks, such as pixel integration and intersection, through dynamic switching of logic functions.</p>