<p>Longan byproducts amount to approximately 1 Mt of waste annually, and sustainability demands have sparked interest in their valorization due to their phytochemical content, including polysaccharides and phenolics. Despite their potential to generate valuable ingredients for the functional food, pharmaceutical, and cosmeceutical industries, their valorization approaches have yet to be comprehensively examined. This study aims to review recent developments in the sustainable valorization of longan byproducts and to examine mechanistic green extraction technologies. Recent studies indicated the potential utilization of longan byproducts in traditional medicine, aquaculture feed, nutraceuticals, food preservation, cosmetics and skincare, food packaging, and other packaging materials. Ultrasound-, enzyme-, high hydrostatic pressure-, pulsed electric field-, and microwave-assisted extraction were identified as eco-friendly modern alternatives that enhance extraction efficiency and sustainability. Reported benefits include enhanced growth and immunity in aquaculture, strong antioxidant, antimicrobial, antidiabetic, and anti-tyrosinase activities, and improved food quality and shelf life. Quantitative findings show high phenolic contents (e.g., up to 179&#xa0;mg/g), significant enzyme inhibition (e.g., α-glucosidase IC₅₀ of 25&#xa0;µg/mL), and improved extraction performance when advanced extraction technologies utilized. Also, recent progresses in reutilization and applying modern extraction technologies to longan waste can potentially contribute to sustainability through waste valorization, development of biodegradable materials, and bioethanol production, supporting sustainable food production and circular bioeconomy approaches. Mechanism-aligned extraction of polysaccharides rich in glucose and arabinose, and phenolic fractions enriched with ellagic acid and gallic acid, respectively, have demonstrated potential for efficiency while reducing unnecessary processing severity. Thus, mechanism-guided extraction could improve selectivity, functionality, and reduce energy consumption for scalable sustainability. Longan byproducts represent a sustainable source of bioactive phytochemicals that, when coupled with advanced mechanism-driven extraction technologies, provide a foundation for their scalable application in functional foods, nutraceuticals, and pharmaceutical products. Future efforts are recommended to conduct life-cycle analyses and commercial viability of recently employed extraction technologies, (e.g., microbiota-assisted technique), to identify sustainability and, in turn, commercial viability.</p> Graphical Abstract <p></p>