The biogenic engineered silver nanoparticles (AgNPs) were synthesized using aqueous extract of marine mangrove Avicennia marina leaves and its anticancer activity was checked in lung cancer cell line. Initially, the UV-vis spectra exhibited the characteristics SPR absorption peak for AgNPs at 425 nm and further characterized using TEM, SAED, XRD and FT-IR analysis. The TEM pictures displayed the spherical crystalline and monodispersed nature of AgNPs and the size range observed between 25-30 nm. The SAED showed the AgNPs are face-centered cubic pattern which is further confirmed with XRD analysis. The FTIR spectral analysis exposed the presence of necessary biomolecules for the reduction and stabilization of silver ions. Synthesized AgNPs showed dose-dependent cytotoxic activity in A549 cell line. The fluorescence studies showed that AgNPs induces apoptosis by increasing the generation of ROS in mitochondria and cleaving the mitochondrial membrane of A549 cells. Further, the molecular studies were conducted using RT-PCR and western blotting analysis and the results confirmed that the AgNPs induce apoptosis through both p53-dependent and -independent caspase intermediated signaling pathway. Together, the present study concludes that the bioengineered AgNPs can act as a potential therapeutic agent against lung cancer.