The aims of the study are to perform green synthesis of AgNPs and assessed the variability and differences in the effects of biosynthesized silver nanoparticles on seed germination and seedling vigor in Acacia senegal and Acacia mellifera. The structural properties of the synthesized AgNPs were characterized using powder X-ray diffraction, were average particle size ranging from 26.51 ± 8.72 nm in transmission electron microscopy (TEM), The sharp color change and the emergence of a characteristic peak at 415 nm in the (UV-Vis) spectrum confirm the formation of the AgNPs, The surface topology by Fourier transform infrared spectroscopy (FTIR), morphological properties, size and shape were visualized using Scanning Electron Microscope (SEM). A completely randomized design (CRD) was used for the experiment with four replicates and four treatments consisted of silver nanoparticles at different concentrations of (control, 25, 50, and 75mgL− 1) to improve seed germination characteristics. AgNPs treated seeds showed a high germination rate with normal seedling growth at concentrations (75mgL− 1) in A. mellifera (100%) and A. senegal (72.5%) at the greenhouse, compared to the control set, which recorded (50%) and (27%) A. mellifera and A. senegal at laboratory conditions, respectively. Silver nanoparticles were successfully improved seed germination and seedling growth in the two studied acacia species.