Wearable triboelectric devices have been widely used for sensing and energy harvesting applications, and further improving the compactness will enhance the convenience and comfortability. In this work, an easy-fabricated and compact untethered triboelectric patch is proposed with Polytetrafluoroethylene (PTFE) as triboelectric layer and human body as conductor. We find that the conductive characteristic of human body has negligible influence on the outputs, and the untethered triboelectric patch has good output ability and robustness. The proposed untethered triboelectric patches can work as sensor patches and energy harvester patches. Three typical applications are demonstrated, which are machine learning assisted objects distinguishing with accuracy up to 93.09–94.91 %, wireless communication for sending typical words to a cellphone, and human motions energy harvesting for directly powering electronics or charging an energy storage device.