The rapid expansion of horticultural production has significantly increased the generation of organic residues, including fruit peels, seeds, pomace, stalks, leaves, and unsold produce. While these materials have traditionally been considered waste, contemporary research increasingly recognizes them as valuable feedstocks for the production of bioenergy, biochemicals, functional ingredients, biomaterials, and agricultural inputs. The concept of sustainable valorization through bioconversion technologies aligns with circular economy principles by transforming waste streams into economically valuable and environmentally beneficial products. This review critically examines the current state of horticultural residue bioconversion, focusing on biological, biochemical, and integrated conversion pathways. The study synthesizes existing literature concerning the composition of horticultural residues, extraction of bioactive compounds, microbial transformation processes, anaerobic digestion, bioethanol production, biochar generation, and development of value-added industrial products. Particular emphasis is placed on technological advancements, resource recovery efficiency, sustainability implications, and challenges associated with commercialization. The review identifies major research trends and gaps in process optimization, feedstock variability management, and industrial-scale implementation. Findings indicate that horticultural residues possess substantial potential as renewable resources for bio-based industries, supporting waste minimization, carbon reduction, and sustainable economic development. Future progress depends on integrated biorefinery approaches, technological innovation, and policy support aimed at enhancing circular bioeconomy frameworks.