The current research explored a green approach for the fabrication and in situ immobilization of gold nanoparticles over a polymeric composite of starch combined with sodium lignosulfonate (ST-LS/Au NPs). It also assessed their catalytic activity and anti-cancer effects. The mixed polymeric ST-LS composite functioned as a reducing-stabilizing agent to cap the gold nanoparticles. Field-Emission Scanning Electron Microscopes (FE-SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Energy Dispersive X-ray Electron Spectroscopy (EDX)-elemental mapping, Transmission Electron Microscopy (TEM), and X-ray diffraction (XRD) were used to examine the synthesized ST-LS/Au NPs. The powdered XRD analysis of ST-LS/Au NPs nanoparticles revealed their crystallinity, with distinct peaks observed at 2θ values of 38.4°, 47.6°, 67.2°, and 77.2°. These peaks indicate the presence of pure gold nanoparticles in an fcc lattice. According to JCPDS No. 65-2870, the prominent reflection, consistent with the (111) plane at 38.4, confirms the formation of nanocrystals. TEM images revealed that the ST-LS/Au NPs nanoparticles exhibited a globular shape, averaging approximately 10 nm in size. Additionally, we chose to utilize Suzuki-Miyaura coupling (SMC) reactions to determine and evaluate the catalytic performance/efficacy of the gained ST-LS/gold nanoparticles composite. We could easily utilize this catalyst over 9 times in the catalytic testing period. This catalyst exhibits great applicability and extension for different aryl halides as well. The antioxidant activity was assessed by investigating its potential biological applications through the DPPH (diphenyl-1-picrylhydrazyl) radical scavenging assay, which gave promising results. Additionally, the study expanded to incorporate the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide], aiming to evaluate its effect on the inhibition of growth of human pancreatic and hepatoma cancer cell lines (MIA PaCa2 and HepG2). The results highlighted significant cytotoxic effects.