Wearable smart devices have drawn tremendous attention recently in the fields including conducive clothing, strain sensors and body heaters for thermotherapy and heat preservation. However, the traditional smart devices exhibit poor wearability and flexibility mainly due to the metallic components they contain, including integrated circuits, semiconductors etc. In this work, we report the preparation of multifunctional reduced graphene oxide/ polyester (rGO/PET) fabrics through suction filtration and reduction, using hydriodic acid (HI) and acetic acid based vapour-phase system. As-prepared rGO/PET fabrics showed the square resistance as low as 24.7 Omega/square, when the GO concentration was 3 mg/ml. Meanwhile, the variation of the electrical resistance was insignificant after 100 bending-releasing operations and 10 folding-releasing cycles. When the rGO/PET fabric served as a strain sensor, the rGO/PET fabrics exhibited high sensitivity, remarkable reliability and feasibility. Furthermore, the rGO/PET fabric exhibited efficient electrothermal response, homogeneous temperature distribution and remarkable flexibility as large-area flexible heater. As-prepared fabrics were further analyzed as wearable strain sensors and ultra-fast responding electrothermal heaters, suggesting their great potential as wearable smart devices in personal healthcare applications.