This paper presents new antenna and circuit designs for on-body flexible electronics. We firstly introduce a stretchable 3D meshed patch antenna which can greatly mitigate the frequency detuning effect when 20% strain force is applied. A new meshing and selective bonding structure has been designed to help maintain the electromagnetic performance of the antenna against diverse mechanical strains. Secondly, we showcase another textile patch antenna design, where its feeding aperture has been miniaturized by exploiting a novel inductive loading technique. The textile antenna is able to accommodate contactless integration of highly efficient rectifier circuits, thereby enabling effective energy harvesting for wearable electronics through low-power RF signals. Both designs will enhance the on-body flexible electronics from a number of aspects, namely, wireless signal connectivity, circuit efficiency and performance stability.