The synthesis of benzimidazoles, a class of heterocyclic compounds with diverse applications in pharmaceuticals, agrochemicals, and materials science, traditionally involves the use of solvents that are often toxic and environmentally harmful. This study presents a sustainable approach to benzimidazole synthesis using solvent-free reactions and renewable feedstocks derived from biomass. The reaction involves the condensation of o-phenylenediamine with carboxylic acids or their derivatives under mild conditions, facilitated by solid catalysts derived from natural sources. The use of renewable feedstocks and solvent-free conditions not only reduces the environmental impact of the synthesis but also enhances the sustainability of the process. The synthesized benzimidazoles are characterized by spectroscopic methods, confirming their structural identity. Biological activities of the synthesized compounds are evaluated, demonstrating their potential applications in drug discovery and other fields. This green synthetic approach offers a sustainable alternative for the synthesis of benzimidazoles, highlighting the benefits of green chemistry in organic synthesis and providing insights for future research in sustainable methodologies.