Light-material interaction has received significant attention for wearable electronics because of its exceptional ability to excite multi-physical, transient, and non-equilibrium photon interactions in a spatiotemporally controlled manner. It has realized unique photothermal and photochemical reactions with various types of materials, including metal nanomaterials, ceramics, graphene, polymers, and perovskites, enabling the substantial performance improvement of soft electronics without damaging a temperature-sensitive substrates. Among the numerous optical sources, flash lamps have been considered to be a suitable platform for commercial applications owing to their excellent light-output efficiency, rapid processing capability, and outstanding compatibility with large-scale roll-to-roll manufacturing. These exclusive features offer considerable advantages in a broad range of wearable and flexible electronics such as solar cells, thin-film-transistors, optoelectronics, and sensors on polymer substrates compared to the conventional high-temperature microfabrication processes. The flash lamp technology has consistently advanced to provide novel concepts of nanomaterials/devices with unlimited form factors and strategies for future wearable electronics. Here, the recent progress in the field of flashlight-material interaction for soft electronics is summarized with regard to the process parameters, materials, and devices, together with the latest updates on the flash lamp technology.