Due to their distinctive optical, electrical, and catalytic characteristics, gold nanoparticles (AuNPs) have found increasing use for a wide range of applications, including biomedicine and catalysis. Inherent agglomeration propensities impair their functional qualities, stability, and biocompatibility. This work investigates the potential applications of the cataractous eye protein isolate (CEPI), a waste product rich in proteins from cataract surgery, as a novel AuNP stabilizing agent. It was found that CEPI can successfully stabilize AuNPs under a variety of situations, preventing ethanol-induced aggregation and preserving their structural integrity. Using spectroscopic and analytical techniques, including UV-Vis spectroscopy, dynamic light scattering (DLS), circular dichroism (CD) spectroscopy, and fluorescence quenching studies, we confirmed the successful binding of CEPI to AuNPs and the enhanced stability of the conjugates. A shift in the localized surface plasmon resonance (LSPR) peak and modifications to the secondary structure of the CEPI were indicative of strong binding and protective effects between CEPI and AuNPs. These findings suggest that CEPI, an underutilized biomaterial, can serve as an effective and biocompatible stabilizer for AuNPs, with potential applications in biomedical and therapeutic fields.