Triboelectric nanogenerators (TENGs) efficiently convert mechanical energy into electricity, offering unique advantages for powering wearable electronics. Key objectives for wearable TENGs include flexibility, and high power density output. Liquid metals (LMs) are emerging as a category of functional materials with both metallic and liquid properties at room temperature, which opens up broader opportunities for TENG applications. Herein, a concept is proposed for constructing a fully flexible triboelectric nanogenerator array for mechanical energy harvesting by using LMs. The LMs layers are embedded in a porous polytetrafluoroethylene (p-PTFE) film, resulting in a series of parallel friction interface arrays. The strong electronegativity of PTFE and the high electronic activity of liquid metals are explored, and the interface at the solid-liquid-gas three-phase junction is constructed to facilitate the energy conversion. Using mechanical triggering, the direct current pulse is generated and amplified at the solid-liquid interface, resulting in an open-circuit voltage (Voc) of 1080 V and a power density (Pmax) of 12.44 W m−2. Furthermore, Voc generated by the device in the contact-separation mode amounted to 1690 V under ultrasonic (40 kHz) excitation. Consequently, this finding is anticipated to offer new opportunities in applications such as flexible electronics, mechanical energy conversion, and human-machine interaction interfaces.