<p>The rapid evolution of wearable technology, interconnected devices, and medical devices is driving innovation in advanced materials for flexible optoelectronics. III-nitride semiconductors, with their exceptional optoelectronic properties, strong piezotronic and piezo-phototronic effects, biocompatibility, and thermal/chemical/mechanical stability, present a compelling alternative to traditional organic and Si-based inorganic materials. Despite significant research efforts, a systematic review summarizing the advancements and challenges in III-nitride flexible optoelectronics is lacking. This article provides a comprehensive overview of recent developments in this field. It begins by highlighting the advantages of III-nitride semiconductors for flexible optoelectronics. The article then discusses the fabrication techniques for III-nitride flexible devices, covering materials growth, film exfoliation and transfer, as well as functional micro/nanostructures. A wide range of flexible applications of III-nitrides are explored, including flexible displays, implantable optogenetic devices, wearable photodetectors, and flexible mechanical sensors. Finally, challenges and potential solutions related to device fabrication, performance enhancement, theoretical modeling, and system integration are discussed. This work serves as a foundational reference and roadmap for further advancements in III-nitride flexible optoelectronics.</p>