Green hydrogen production through hydroxide exchange membrane water electrolysis (HEMWE) is a crucial step in achieving sustainable energy transition and carbon neutrality goals. Despite the numerous advantages of HEMWE, including high performance and low cost, challenges such as low in-situ stability have been inhibiting its commercialization. This article focuses on addressing the in-situ stability issue by developing a 3D thermally conductive network in HEM using boron nitride nanosheets. The study reveals that the inferior in-situ stability of HEM is primarily caused by inhomogeneous heat accumulation and high localized temperatures during water electrolysis due to the low thermal conductivity of the membranes. By incorporating a 3D thermally conductive network, the thermal conductivity of HEM is significantly enhanced, leading to improved in-situ stability and durability. This advancement allows for water electrolysis with almost no degradation, bridging the gap between in-situ and ex-situ stability. Through simulations and experimental data, the researchers demonstrate the impact of thermal conductivity on HEM in-situ stability, highlighting the importance of efficient heat diffusion. The findings not only provide insights into enhancing HEMWE for green hydrogen production but also offer a pathway for designing ion-exchange membranes for various energy conversion and storage applications. Overall, this study's positive outcomes in improving the in-situ stability of HEM pave the way for the wider implementation of green hydrogen production technologies and contribute to the ongoing efforts in achieving a sustainable and carbon-neutral future.