This study conducts a high-fidelity two-way coupled fluid–structure interaction simulations, focusing on a novel perforated elastic vortex generator that is wall-mounted in an open channel with an incoming flow. The response of a perforated elastic vortex generator is investigated across a wide range of dimensionless parameters including dimensionless rigidity, mass ratios, Reynolds numbers, and porosity levels. Additional simulations for non-perforated elastic vortex generator are conducted for comparison and validation against available data. The findings demonstrate that a perforated elastic vortex generator can exhibit static configurations, lodging configurations, and vortex-induced vibration modes, depending on the dimensionless parameters. These configurations are similar to those observed for non-perforated elastic vortex generators, though the response values differ due to changes in the mechanical properties of the elastic vortex generator and the fluid loads acting on it as a result of perforation. An analysis of the perforated elastic vortex generator's natural frequencies shows that vortex-induced vibrations are triggered by the lock-in phenomenon associated with the second natural frequency of the vortex generator. Additionally, local flow dynamics are also studied by investigating vortical structures and velocity fields.