Abstract: With continuous innovations in technologies such as flexible wearable electronics and human motion sensors, there is a growing demand for functional hydrogels that combine excellent electrical conductivity, good mechanical adaptability, and environmental stability. Intrinsically conductive polymer hydrogels—which do not require the addition of conductive media and possess inherent conductivity—combine the electroactivity of conductive polymers with the flexibility of hydrogels, making them a core research focus for the next generation of flexible conductive materials. This paper systematically reviews the molecular structures, conductive mechanisms, and differences in physicochemical properties of intrinsically conductive polymers, summarizes mainstream preparation strategies such as in-situ polymerization and physical blending, and then focuses on the specific classification and preparation methods of three typical materials—polypyrrole, polyaniline, and PEDOT:PSS. It provides an in-depth analysis of the core issues associated with each, summarizes their common challenges, and offers solutions. In addition, other traditional conductive polymers, such as polyindole and polythiophene, are briefly introduced. Based on the inherent properties of intrinsically conductive hydrogels, their suitable application scenarios are further identified. Finally, current challenges are summarized, and future development directions—including green synthesis, multifunctional integration, and application translation—are outlined.