Non-immersed cavitation jets represent an advanced surface treatment technology, characterized by their ability to generate cavitation in an air environment. Owing to their simple structure, these jets have found widespread application. In this study, both numerical and experimental investigations of non-immersed cavitation jets, incorporating fluid–solid coupling, are conducted. The microforming effects on T2 copper foils, induced by non-immersed cavitation jets, are analyzed by comparing simulation results with the experimental data, thereby validating the efficacy of this technique in foil microforming. Additionally, the flow field characteristics of the non-immersed cavitation jet are examined, focusing on the transient distributions of velocity, vortex structures, cavitation bubbles, and pressure at various dimensionless impact distances. The findings confirm that non-immersed cavitation jets are effective for microforming T2 copper foils, with an optimal dimensionless impact distance of 40 under the specified process parameters. The study also reveals that the non-immersed cavitation jet flow is inherently unstable, with the impact distance significantly influencing the evolution of vortex structures and cavitation bubbles. This research offers critical insights into the physical mechanisms underlying non-immersed cavitation jet microforming and provides both a theoretical foundation and experimental guidance for optimizing jet parameters to enhance microforming precision in future applications.