The static mechanical properties of conventional rigid and emerging soft electronics offer robust handling and interfacing mechanisms and highly compliant and adapting structures, respectively, but limit their functionalities and versatility. Mechanically transformative electronics systems (TESs) have extensive potential applications beyond these existing electronics technology owing to their ability to achieve both rigid and soft features as a result of bidirectional reconfiguration of their mechanical structure under the influence of stimuli (e.g. heat, electric/magnetic field, light, stress). In this article, we review recent advances in materials and fabrication methods as well as their applications for the development of TESs. We present key requirements for TESs and cover a range of stimuli-responsive materials and design strategies. Potential applications with demonstrated utility in wearables, implantable devices, sensors, and robotics, alongside key challenges and opportunities in the develop-ment of this emerging technology, are also discussed. (c) 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).