Developing multifunctional supramolecular adhesives, capable of instant underwater adhesion and multi-responsive sensing, is crucial for marine exploitation. However, producing underwater conductive adhesives that can effectively bind and conform to the complex contours of substrate surfaces is challenging. Herein, drawing inspiration from traditional gourmet “gluten” processing, we devised an “one-pot kneading-washing” supramolecular assembly strategy to engineer a shape-adaptive multifunctional underwater electroactive adhesive (e-PT/GS) for underwater sensing/communication and leakage sealing. Utilizing multiple non-covalent interactions, e-PT/GS demonstrated excellent electrical conductivity, underwater self-healing capability, anti-swelling properties, and the ability to achieve rapid, stable, and long-lasting underwater adhesion to a wide range of substrates in various harsh environments (e.g., acids, alkalis, seawater, and salt solutions). E-PT/GS exhibited anticipative shape-adaptability, repelling interfacial water and filling irregularities on the substrate surface, thereby establishing tight and unprecedentedly adaptable underwater contact with the substrates. In combination with the multi-dimensional sensing origins, e-PT/GS was utilized for underwater sealing and in-situ real-time monitoring of signals from the sealing points. Additionally, it was applied in body motion perception, wireless and underwater communications and enabled the collection of steady and authentic ECG signals. The proposed novel strategy is expected to significantly advance the design and applications of the next-generation conductive underwater adhesives.