Abstract: By altering the near-wall flow state of ships to achieve desired mechanical effects, this constitutes an advanced technical approach for improving the hydrodynamic performance of marine vehicles. In this study, a precision flow-observation water tunnel was used to investigate the flow behavior of bubbles constrained by a flat plate under crossflow conditions. By regulating two key flow parameters—ventilation rate and crossflow velocity—and employing high-speed imaging along with Particle Image Velocimetry (PIV), the evolution of the near-wall gas–liquid two-phase flow structure and the mechanisms governing bubble shedding phenomena. Experimental results show that under the defined conditions, bubbles detach primarily via orifice-detached and necking off-detached. PIV measurements indicate that during bubble growth, positive vorticity develops at the bubble’s leading edge. From the flow field images of the two shedding flow regimes, it can be observed that during the streamwise growth stage of bubbles, a positive vorticity region develops at the front head of the bubble. At the moment of bubble detachment and fragmentation, the vertical velocity component at this specific location exhibits a vertically upward direction, subsequently inducing local negative vorticity. Further statistical analysis demonstrates that under varying crossflow Reynolds numbers and ventilation coefficients, regular variations are observed in bubble shedding frequency, length, and thickness.