In the presence work, silver nanoparticles were synthesized by a facile green procedure using Pistacia atlantica bark extract as natural reducing and pectin as stabilizing reagent. The physicochemical characteristics of the synthesized Pectin/Ag NPs are further confirmed by several characterization methods such as FT-IR, XRD, FESEM-EDX and TEM analyses. The Fourier transform infrared spectrometer was utilized to investigate the functional groups present in pectin capped silver nanoparticles that were responsible for the capping and remarkably dispersed nanoparticles with no aggregation. The latest research concentrated on the cellular and molecular components. The MTT test was done to assess the effectiveness of the Pectin/Ag NPs nanocomposite on inhibiting human gastric cancer cells and its cytotoxic effects on the treated cells. The evaluation was conducted on healthy (HUVEC) and stomach cancer cells, specifically NCI-N87 and MKN45. The nanocomposite exhibited IC50 values of 75 µg/mL against MKN45 and 152 µg/mL against NCI-N87. A decrease in the viability of gastric cancer cells was noted in the nanocomposite presence, which was dependent on the dosage. Additionally, the nanocomposite triggered a 70–90 % increase in cell apoptosis, resulting in elevated levels of pro-apoptotic markers (Bax and cleaved caspase-8) and reduced levels of the anti-apoptotic marker, Bcl-2. The Pectin/Ag NPs exhibited suppressive properties on colony formation. Our findings suggest that the Pectin/Ag NPs have the ability to enhance p53 expression while reducing the STAT3 expression in the cells that were treated. The findings suggest that STAT3 and p53 are essential factors in the biological responses triggered by the extract in human gastric carcinoma cells. The results suggest that the nanocomposite has the potential to serve as an effective treatment for human gastric cancer cells.