Electrophysiological signals are fundamental to elucidating the functional states and pathological mechanisms of the cardiac and nervous system. Yet, conventional techniques are constrained by inherent trade-offs between high-throughput capabilities, signal-to-noise ratio (SNR), and long-term stability. To address these challenges, field-effect transistor (FET)-based electrophysiological sensors have gained prominence as a powerful platform for cardiac and neural monitoring, distinguished by their exceptional sensitivity, low intrinsic noise, and superior spatiotemporal resolution. Here, we present a comprehensive overview of recent advances in this field, differentiating between planar and three-dimensional architectures to highlight distinct design strategies and applications. Specifically, planar configurations leverage rigid substrates for high-density integration and in vitro electrophysiological analysis, while flexible planar FETs, including graphene and organic transistors, enable conformal wearable and implantable monitoring. Conversely, three-dimensional configurations leverage nanoscale probes or mesh scaffolds to achieve intimate cell-device interfaces, enabling high-fidelity intracellular recording. Beyond device geometry, the integration of emerging materials, including graphene and organic semiconductors, is critically examined, along with the material, interfacial, and device-level factors that govern noise, SNR, and long-term sensing stability. The review concludes with an outlook on current challenges and future opportunities, emphasizing chronic biointerfacing, scalable integration, and reliable in vivo operation as key steps toward clinical translation in cardiology and neuroscience.