Recently, significant efforts have been directed at overcoming the limitations of conventional rigid optoelectronic devices, particularly their poor mechanical stability under bending, folding, and stretching deformations. One of major approaches for rendering optoelectronic devices mechanically deformable is to replace the conventional electronic/optoelectronic materials with functional nanomaterials or organic materials that are intrinsically flexible/stretchable. Further, advanced device designs and unconventional fabrication methods have also contributed to the development of soft optoelectronic devices. Accordingly, new devices such as bio-inspired curved image sensors, wearable light emitting devices, and deformable bio-integrated optoelectronic devices have been developed. In this review, recent progress in the development of soft optoelectronic materials and devices is outlined. First, various materials such as nanomaterials, organic materials, and their hybrids that are suitable for developing deformable photodetectors, are presented. Then, the nanomaterials and organic/polymeric materials that are applicable in deformable light-emitting diodes are described. Finally, representative system-level applications of flexible and stretchable photodetectors and light-emitting diodes are reviewed, and future prospects are discussed.