<p>In pursuit of greener synthetic methodologies, we report the design and development of a novel palladium(II) Schiff-base complex tethered to guar gum (GG) as an environmentally benign, solid-supported catalyst for Suzuki–Miyaura cross-coupling reactions. The biopolymer-supported catalyst (Pd–Schiff base@GG) was prepared via covalent grafting of a Schiff-base ligand onto the guar gum backbone, followed by coordination with Pd(II). Comprehensive characterization using FT-IR, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), SEM–EDS elemental mapping, and thermogravimetric analysis (TGA) confirmed successful ligand immobilization, uniform palladium dispersion, and good thermal stability. XRD analysis revealed the predominantly amorphous nature of the polymeric matrix with weak Pd-related features, while XPS confirmed palladium exclusively in the + 2 oxidation state, indicating strong coordination within the Schiff-base-functionalized guar gum framework. The catalyst exhibited excellent activity and selectivity across a broad range of aryl halides and phenylboronic acids in aqueous and green solvent systems under mild conditions, delivering high turnover numbers. Notably, the catalyst demonstrated good recyclability and structural stability over multiple cycles, with hot-filtration experiments confirming its true heterogeneous nature and negligible Pd leaching. This biopolymer-based catalytic platform adheres to the principles of green chemistry by employing a renewable support, minimizing waste, avoiding toxic solvents, and enabling efficient catalyst recovery and reuse, offering a sustainable approach for C–C bond formation.</p>