Experimental exploration of strained nanostructures, such as nanowires and bio-molecules, is essential for understanding their properties. However, the ability to apply and to quantify nanometer displacements is challenging. We present a novel MEMS nano-extensometer with integrated actuation and compliant de-amplification mechanism allowing the accurate characterization of stretched nanostructures. A feasibility study was followed by fabrication and characterization of the device. The deamplified displacement was registered via optical microscopy and was processed using an improved digital image correlation algorithm to achieve nanometer measurement accuracy. Using our technique, nanoscale displacement can be determined by means of simple imaging tools. This was demonstrated by stretching suspended single wall carbon nanotubes.