Electrochemical metallization threshold switch (ECM TS) has received significant attention for various applications owing to its high ON/OFF ratio, fast switching characteristics, and simple active electrode/dielectric layer/inert electrode structures. However, the excess diffusion of active metal ions causes severe variation in threshold voltage and poor endurance. Furthermore, the small room for inert electrode metal is a problem to be solved for various applications of ECM TS. Here, a novel structure is proposed in which a two‐dimensional platinum diselenide (PtSe2) is inserted between the dielectric layer and inert electrode to engineer the conductive filament by controlling the active metal ion concentration. The low work function, superior inertness, layered structure, and smooth surface of PtSe2 insertion layer lead to thin and weak conductive filament with few active metal atoms and allow the use of various metals as inert electrode. Consequently, PtSe2‐inserted ECM TS shows high reliability in both threshold voltage distribution (σ/µ = ≈6.58%) and endurance (>106 cycles). Furthermore, PtSe2‐inserted ECM TS‐based 2 × 2 cross‐bar array is proposed as AND and OR logic circuits. This study is expected to pave the way for the development of ECM TS for next‐generation electronic applications.