Robust power supplies and self‐powered sensors that are extensible, autonomously adhesive, and transparent are highly desirable for next‐generation electronic/energy/robotic applications. In the work, a solid‐state triboelectric patch integrated with the above features (≈318% elongation, >85% average transmission, ≈44.3 N m−1 adhesive strength) is developed using polyethylene oxide/waterborne polyurethane/phytic acid composite (abbreviated as PWP composite) as an effective current collector and silicone rubber as tribolayer. The PWP composite is optimized systematically and corresponding single‐electrode device can supply a power density of 2.3 W m−2 at 75% strain. The triboelectric patch is capable of charging capacitors and powering electronics by efficiently harvesting biomechanical energies. Moreover, it can be autonomously attached to nonplanar skin or apparel substrates and used as a tactile sensor or an epidermal input touchpad for physiological motion detection and remote control of appliances, respectively. Even after dynamic deformation, tailoring, and prolonged use, the patch can maintain good stability and reliability of electrical outputs. This work provides a novel solid‐state and liquid‐free polyionic electrode‐based triboelectric nanogenerator integrated with adhesiveness, stretchability, and transparency, which can meet wide application needs from transparent electronics, artificial skins, to smart interfaces.