Abstract In the field of reinforced concrete structures, there is a growing need for structural engineers to develop methods that raise the shear punching capacity of existing flat slabs. Unfortunately, current structural solutions that aim to enhance the shear punching capacity suffer from many technical and economic problems. The aim of this paper is to develop a new and more efficient method for raising the shear punching capacity of existing concrete structures. The main idea behind this new strengthening method is to use post installed concrete screws as a punching reinforcement. This new strengthening method was analysed within an experimental framework performing shear punching tests on samples containing post-installed concrete screws. In addition to experimental tests, numerical simulations, based on the finite element method, were executed to derive a simplified model to calculate the shear punching capacity of strengthened slabs. In comparison to currently available structural methods, this new method, based on the use of post installed concrete screws, satisfies much of the criteria required for effective structural reinforcement. Along with robustness and economic efficiency, this new strengthening method leads to a significant increase in shear punching capacity.