The escalating global prevalence of obesity underscores the need for effective and sustainable nutritional interventions. Functional foods, especially white kidney beans (Phaseolus vulgaris), show a promising avenue to link fundamental biochemical insights with clinically feasible interventions, supporting their potential as an adjunct dietary strategy for managing and preventing obesity. This review critically examines the mechanistic roles of white kidney bean in weight regulation, which includes suppression of starch digestion, attenuation of postprandial glycemia, modulation of appetite and satiety, and hypolipidemic effects. Clinical and preclinical evidence supports the potential of white kidney bean as a nutraceutical for metabolic health, demonstrating consistent reductions in body fat mass, glycemic excursion, and overall weight. Nevertheless, significant limitations persist, including heterogeneity in trial designs, absence of dose standardization, and inadequate long-term safety assessments. Furthermore, this review addresses food fortification, advancements in supplement formulation, and cooking techniques that enhance both consumer acceptability and the bioactivity of white kidney bean (WKB), along with the significance of regulatory standards to ensure safety and quality. Future research should integrate clinical, molecular and food technology methods to improve the translation of experimental findings into precision nutritional strategies for obesity management.