<p>The demand for new sources of plant-based protein has been steadily increasing. In this context, researchers worldwide have explored green biomass, an agro-industrial waste product derived from diverse crops, as a viable alternative for sustainable protein production since 2014. As a result, studies have been conducted to explore the acquisition of leaf protein concentrates (LPCs) and their derivatives, including peptides and protein fractions, through both traditional methods and innovative techniques for potential applications in various fields. This review highlights the most relevant research from the past decade on extracting and enhancing the techno-functionality and bioactivity of LPCs, peptides, and protein fractions derived from diverse biomass. It provides a comparative analysis of the composition, nutritional profiles, and functional/bioactive characteristics of LPCs sourced from different biomass origins, while detailing the methods employed for extraction, modification, and property analysis of these proteins, emphasizing the practical advancements related to their applications. These applications involve developing antimicrobial films and functional foods, their effectiveness as emulsifiers in O/W emulsions, and their roles in micro/nanoencapsulation techniques, such as spray drying and electrohydrodynamic processes. In addition, the potential of LPCs and their derivatives as antioxidant and antiproliferative agents, along with their importance in the field of aquaculture, was also recognized. This review demonstrated the significant potential of green biomass proteins for several applications. Industrial-scale production may become feasible in the future through biorefinery processes, which not only ensure economically viable production but also offer a plant-based protein alternative to traditional sources.</p> Graphical Abstract <p></p>