AbstractAlthough 2D materials are widely explored for data storage and neuromorphic computing, the construction of 2D material‐based memory devices with optoelectronic responsivity in the short‐wave infrared (SWIR) region for in‐sensor reservoir computing (RC) at the optical communication band still remains a big challenge. In this work, an electronic/optoelectronic memory device enabled by tellurium‐based 2D van der Waals (vdW) heterostructure is reported, where the ferroelectric CuInP₂S₆ and tellurium channel endow this device with both the long‐term potentiation/depression by voltage pulses and short‐term potentiation by 1550 nm laser pulses (a typical wavelength in the conventional fiber optical communication band). Leveraging the rich dynamics, a fully memristive in‐sensor RC system that can simultaneously sense, decode, and learn messages transmitted by optical fibers is demonstrated. The reported 2D vdW heterostructure‐based memory featuring both the long‐term and short‐term memory behaviors using electrical and optical pulses in SWIR region has not only complemented the wide spectrum of applications of 2D materials family in electronics/optoelectronics but also paves the way for future smart signal processing systems at the edge.