Plant proteins have drawn more interest as nutritious, renewable macromolecules with substantial technological and functional promise. Their physicochemical behaviour and consequent functional qualities in food systems are directly governed by their structural complexity, which includes fundamental amino acid sequences, secondary motifs, tertiary folding patterns, and quaternary relationships. Molecular weight distribution, surface hydrophobicity, charge distribution, and conformational flexibility are all inherently related to variations in solubility, emulsification, foaming, gelation, and water/oil binding capabilities. The structural alterations due to botanical source, processing, and modification techniques can further modulate these functional properties. The structure–function interactions of plant proteins can be studied by advanced analytical techniques such as FTIR, circular dichroism, fluorescence spectroscopy, electrophoresis, thermal analysis, and rheological profiling. This chapter summarizes the science regarding the structural and functional interdependence of plant proteins, emphasizing case studies and mechanistic evidence. It also provides insights into the engineering techniques and targeted modifications for improving its range of applications in the food industry.