<p>Organic transistors have emerged as a versatile device platform at the interface of conventional microelectronics and emerging bioelectronics. Two archetypes, organic field-effect transistors (OFETs) and organic electrochemical transistors (OECTs), embody distinct yet complementary operating principles. OFETs rely on electrostatic modulation for high-speed switching and reliable performance in dry environments, making them suitable for displays and logic circuits. In contrast, OECTs leverage volumetric ion–electron interactions for ultra-low voltage operation and high transconductance, excelling in biosensing and wearable applications under aqueous conditions. Both device classes are solution-processable and mechanically flexible, but suffer from intrinsic limitations like bias stress and electrochemical degradation. Accordingly, their most impactful applications are anticipated in low-cost, disposable devices such as point-of-care diagnostics and flexible biosensors, rather than high-end, cost-intensive sectors. This review provides a comprehensive analysis of their evolution, offering a framework for future materials design.</p>