The current development was focused on environmentally friendly and cost-effective synthesis of silver nanoparticles (AgNPs). This investigation aims to synthesize AgNPs using Anchusa arvensis aqueous plant extract. The characterization was confirmed by means of different techniques including, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FT-IR) Spectroscopy, and UV-visible analysis. The crystalline morphology of AgNPs is demonstrated by X-ray diffraction, with mean crystallite diameter ranges from 20–25 nm. The spherical geometry of particles was revealed via SEM images. The FT-IR Spectroscopy confirmed that, aqueous extract of plant contains essentials phytoconstituents such as, O–H stretching vibration of carboxylic acid, C–H is the stretching vibration of alkane, C–O indicate the stretching vibration of alcohol, C=C corresponds to stretching vibration of aromatic compounds, which were responsible for the formation of AgNPs. The synthesized nanoparticles were stable at temperatures up to 50 °C, as well as in neutral and basic pH, but were unstable at acidic pH. The synthesized AgNPs had promising antileishmanial and THP-1 Cell line cytotoxic activity against Leishmanial promastigotes, with an averaged mortality (%) of 85.3±0.7% at IC50 values of 35.3±1.81 μg/mL and 65.3±0.7% with IC50 values of 45.3±1.81 μg/mL, respectively. The brine shrimp lethality of synthesized nanoparticles showed that the concentration greater than 200 μg/mL was biologically compatible.