Additive manufacturing can rapidly and directly produce metal parts with complex geometries, while significantly improving material utilization and reducing costs. Additive manufacturing parts still have a certain gap with forgings in key properties such as fatigue, and it is necessary to find an effective post-processing method. Additive manufactured TC4 was treated by laser peening, and the surface integrity improvement effect of TC4 titanium alloy was investigated. The strengthening effect was compared with the same grade conventional forged titanium alloy. The results show that laser peening has little effect on the surface roughness of the two materials. Furthermore, the surface microhardness of additive manufactured TC4 increased from 348 HV to 367 HV, and the hardening layer reached a thickness of 0.75 mm, while the surface microhardness of wrought TC4 increased from 315 HV to 362 HV, and the hardening layer reached a thickness more than 1 mm. Compressive residual stress was induced into the subsurface of the samples with a maximum value around 400 MPa for the additive manufactured TC4. The affected zone depth was around 0.75 mm. For the wrought TC4, the compressive residual stress was induced into the subsurface of the samples with a maximum value around 600 MPa. The affected zone depth was more than 1 mm. In addition, the density of additive manufactured TC4 was measured by the Archimedes method. The density of additive manufactured TC4 was 98.46%, while the density became 98.92% after one shock of laser peening. Compared with wrought TC4, the relative porosity of additive manufactured TC4 may be the reason for the smaller residual stress amplitude and shallow affected depth by laser peening.