Cancer is a major worldwide health concern therefore warranting the development of new and effective therapeutic options. The potential anti-cancer capabilities of silver nanoparticles (AgNPs) derived from medicinal plants have garnered significant attention in recent times. the present work aims to evaluate an in vivo anti-cancer efficacy in the Mouse Lewis lung carcinoma (LLC1) lung tumour model accompanied with an in vivo safe dose selection study in C57BL/6 mice. The safe dose of REMAG for anti-cancer activity was tested at three doses, viz., low (10 mg/kg), mid (30 mg/kg) and high (60 mg/kg) dose in C57BL/6 mice (male and female). The biogenic AgNPs were found to be biocompatible with no abnormal body weight changes, clinical signs, and gross pathological observations in healthy male and female mice. An excellent tumor inhibition response of 77% was obtained at the selected dose of 50 mg/kg in the LLC1 tumour allograft model. The outcomes propose the promising candidature of synthesized AgNPs for anti-cancer efficacy and future studies are warranted in other cancer cell lines and for its molecular mechanism of actions.