<p>Additively manufactured materials (AM) built by the laser powder bed fusion process (LPBF) suffer from poor surface integrity, including pores, tensile residual stress, and a rough surface, which limits their structural properties in load-bearing applications. Burnishing in the presence of ultrasonic vibration can serve as a surface treatment method that can enhance the properties of AM material to an acceptable level. However, the mechanism of enhancing the structural integrity in the burnishing process has not been completely investigated and requires further investigation. In the present work, experimental studies were conducted to investigate the effect of ultrasonic-assisted ball burnishing on the fatigue and stress–strain behavior of AISI 316L AM material produced by LPBF. Accordingly, a series of experiments taking into account the effect of vibration amplitude, static force, feed rate, and spindle speed as inputs of the process were carried out using response surface design, and the low-cycle fatigue life, ultimate tensile strength, and elongation at peak were measured as outputs of the process. The optimum parameter setting was then obtained, and its structural properties were compared to as-built samples. Furthermore, the improvement of the structural properties was justified using the microscopic aspects of surface integrity, aspects like roughness, porosity, residual stress, and microstructure development. The obtained results revealed that the selection of settings comprising the vibration amplitude of 30&#xa0;μm, static force of 400 N, spindle speed of 100 RPM, and feed rate of 0.05&#xa0;mm yields the best results, meeting all the load-bearing characteristics where 100% improvement of fatigue, 48% improvement in UTS, and 69% improvement in elongation at peak is achieved. It can be attributed to the reduction of density, changing the surface residual stress from tensile to compressive type, microstructure refinement, and better surface quality.</p>