Recent advancements in the integration of nanoscale, single-crystalline semiconductor ‘X’ on substrate ‘Y’ (XoY) for use in transistor and sensor applications are presented. XoY is a generic materials framework for enabling the fabrication of various novel devices, without the constraints of the original growth substrates. Two specific XoY process schemes, along with their associated materials, device and applications are presented. In one example, the layer transfer of ultrathin III–V semiconductors with thicknesses of just a few nanometers on Si substrates is explored for use as energy-efficient electronics, with the fabricated devices exhibiting excellent electrical properties. In the second example, contact printing of nanowire-arrays on thin, bendable substrates for use as artificial electronic-skin is presented. Here, the devices are capable of conformably covering any surface, and providing a real-time, two-dimensional mapping of external stimuli for the realization of smart functional surfaces. This work is an example of the emerging field of “translational nanotechnology” as it bridges basic science of nanomaterials with practical applications.