The harnessing and utilization of tidal current energy have emerged as prominent topics in scientific inquiry, due to their vast untapped resource potential, leading to numerous investigations into the efficacy of hydrokinetic turbines under various operational conditions. This paper delineates the wake field characteristics and performance of horizontal axis tidal stream turbines under the influence of support structures, using a comprehensively blade-resolved computational fluid dynamics (CFDs) model that employs Reynolds-averaged Navier−Stokes (RANS) equations in combination with the RNG k-ε turbulence model. To achieve this, the study utilized experimental tank tests and numerical simulations to investigate the distribution characteristics and recuperative principles of the turbine’s wake field. The velocity distribution and energy augmentation coefficient of the wake field showed strong agreement with the experimental results. To further assess the effect of support structures on the flow field downstream of the unit and its performance, the hydrodynamic attributes of the turbine wake field were analyzed with and without support structures. The interference elicited by the support structure modified the velocity distribution of the near-wake flow field, resulting in a 4.41% decrease in the turbine’s power coefficient (Cp), significantly impacting the turbine’s instantaneous performance.