The present study reports the chemical synthesis of gold nanoparticles (AuNPs) using sodium borohydride as a reducing and capping agent. The various temperatures and time intervals were investigated for controlled formation of AuNPs. The characterization of AuNPs was studied using UV-vis spectrophotometer, transmission electron microscope (TEM), selected area diffraction (SAED), energy-dispersive X-ray spectrophotometer (Edx), dynamic light scattering (DLS), zeta potential, and X-ray powder diffraction (XRD), and results indicated that AuNPs were spheroid in shape and cubic lattice and face centered in nature with 29 nm in size. AuNPs have potential antimicrobial activity against selected human clinical pathogens. IC 50 concentration of AuNPs was determined as 20 μg/ml against non-small cell lung cancer (NSCLC) cell lines using MTT assay. The morphological and apoptosis effects of AuNPs on NSCLC were investigated using acridine orange/ethidium bromide (AO/EB), 2′,7′-dichlorofluorescein-diacetate (DCFH-DA), rhodamine 123, and 4′,6-diamidino-2-phenylindole (DAPI) staining method, and results indicated that AuNPs have potential anticancer activity against NSCLC cell lines. The anticancer activity of AuNPs is that it has less toxicity against human HBL100 normal cells. These anticancer potentials of AuNPs were compared with the standard drug cisplatin. Moreover, after 24 h exposure, AuNPs arrest the cell cycle at G2/M phase in A549 cells. These findings suggested that AuNPs could act as a potential anticancer agent against lung cancer.