Background: Due to their biological and physiochemical characteristics, metal-based nanoparticles show promise as antimicrobials and therapeutic agents. Aim: This study aimed to biosynthesize AuNPs from A. baumannii broth and test their antibacterial and ant-virulence properties. Materials and methods: UV-vis, FTIR, XRD, TEM, FESEM and AMF were used to analyze biosynthesized gold nanoparticles. The well method diffusion assay was utilized to determine Ab-AuNPs' antibacterial activity against five bacterial strains. Microtiter plate was used to study the effect of Ab-AuNPs on biofilm formation in five bacterial isolates. Results Biosynthesized Ab-AuNPs feature 574 nm UV-Visible SPR bands. Ab-AuNPs biosynthesized at 3321.42, 2823.79, 2144.84, 1631.78 cm^-1, amide III, polypeptides, and proteins form these bands. A. baumannii polypeptides capped AuNPs. The peaks at 111, 200, 220, and 311 reflect the 2 Bragg angles 38.18°, 44.51°, 64.80°, and 77.72°. Debye Scherrer's equation calculated Ab-AuNPs crystallite size (26.82 nm). Biosynthesized Ab-AuNPs were 20-90 nm in size, with an average of 66 nm. AFM measures Ab-AuNP shape. AFM images show Ab-AuNP size distribution. Ab-AuNPs averaged 63.82 nm. The diameter of the inhibitory zone decreases with Ab-AuNP concentration. Biosynthesized Ab-AuNPs inhibited biofilm formation in five bacterial strains. Conclusions: We concluded that the biosynthesized Ab-AuNPs have effective antibacterial and antibiofilm activity that could enhance the action of existing antibiotics and could be a therapeutic agent.