Hydrogels with the integrated characteristics of adhesion, self-healing, deformability, and conductivity hold enormous potential for the design of next-generation flexible human body posture sensor and energy device. Here, we proposed a double-network hybrid polyacrylamide/poly(acrylic acid)/MXene/PEDOT:PET (PPMP) hydrogel with excellent flexibility, self-healing capabilities, and stability. Furthermore, the proposed PPMP conductive hydrogel with MXene/PDMS encapsulation layer can play the role of a wearable strain sensor that can be used to detect various dance movement postures, including those of facial expressions, blinking, and elbow joints. Additionally, the proposed PPMP hydrogel with MXene/PDMS encapsulation layer can function as a flexible and stretchable triboelectric nanogenerator (FS-TENG) to harvest human motion energy. The FS-TENG can obtain an open-circuit voltage (Voc) of 169.2 V and a short-circuit current (Isc) of 9.6 µA. Moreover, the electric energy generated by these FS-TENGs can be used to drive hygrothermographs. This research offers a feasible strategy to design self-powered strain sensors for use in dance posture monitoring and energy harvesting in human motion.