Polymeric re-tanning agents are often used to fill and firm leather structure, offering uniform grain and controlled softness without compromising tensile strength. These agents can replace or reduce the use of traditional resins, syntans, and fillers that often contribute to higher chemical oxygen demand (COD) in tannery effluents. Modern polymeric systems are developed with an emphasis on formaldehyde-free formulations, rapid biodegradability, and compatibility with wet-white and chrome-free leathers. They often feature high exhaustion rates and reduce the need for post-treatment chemicals. By improving the evenness and handle of the finished leather, these agents also enhance dye uptake and reduce reprocessing waste. Their versatility supports both fashion and automotive leather applications, where performance and sustainability are tightly linked. B2B networks are instrumental in promoting access to polymeric re-tanning innovations and fostering supplier relationships that prioritize transparency, compliance, and continuous improvement.