With the increasing reliability requirements of aerospace equipment, very high cycle fatigue of TC17 titanium alloy has gained significant attention. This study investigates the effects of different wet shot peening treatments on the surface integrity and very high cycle fatigue performance of TC17 titanium alloy, elucidating the underlying mechanisms. Experimental results show that wet shot peening exacerbates surface defects, increases roughness, creates a plastic deformation layer, and induces compressive residual stress and work hardening. The combined effect of these factors reduces the fatigue performance. However, post-peening polishing significantly enhances the very high cycle fatigue performance by reducing stress concentration from surface defects while retaining the beneficial effects of compressive residual stress. Therefore, polishing after wet shot peening is concluded to be the most effective method for improving the very high cycle fatigue performance of TC17 titanium alloy.