Bulky external power supplies largely limit the continuous long-term application and miniaturization development of smart sensing devices. Here, we fabricate a flexible and wearable integrated sensing system on an electrospun all-nanofiber platform. The three parts of the sensing system are all obtained by a facile ink-based direct writing method. The resistive pressure sensor is realized by decorating MXene sheets on TPU nanofiber. And, the resistive temperature sensor is prepared by compositing MXene sheets into poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The thin-film zinc–air battery (ZAB) includes an interdigital zinc–air electrode that is bonded with a gel polymer electrolyte. It can supply a high open-circuit voltage of 1.39 V and a large areal capacity of 18.2 mAh cm-2 for stable and reliable power-supplying sensing parts operation. Thanks to the hydrophobic nature of TPU and open-ended micropores in the TPU nanofiber, the sensing system is waterproof, self-cleaning, and air and moisture permeable. For application, the above-mentioned functional components are seamlessly integrated into an intelligent electronic wristband, which is comfortably worn on a human wrist to monitor pulse and body temperature in real time with continuous operation of up to 4 h. By the novel design and remarkable performance, the proposed integrated all-nanofiber sensing system presents a promising solution for developing advanced multifunctional wearable electronics. We developed an integrated sensing system on a flexible and breathable thermoplastic polyurethane nanofiber platform. The sensing system is realized by a direct write technology and includes a pressure sensor, temperature sensor, and rechargeable zinc–air battery. The integrated sensing system was designed for wristbands and demonstrated to accurately detect pulse beating and skin temperature under different states for up to 4 hours of wearing.