Submerged abrasive waterjet peening (SAWJP) is an effective anti-fatigue manufacturing technology that is widely used to strengthen aeroengine components. This study investigated the correlation of SAWJP process parameters on surface integrity and fatigue life of titanium alloy TA19. SAWJP with different water pressures and standoff distances (SoDs) was conducted on the TA19 specimens. The surface integrity of the specimens before and after SAWJP with different process parameters was experimentally studied, including microstructure, surface roughness, microhardness, and compressive residual stress (CRS). Finally, fatigue tests of the specimens before and after SAWJP treatment with different process parameters were carried out at room temperature. The results highlighted that the fatigue life of the TA19 specimen can be increased by 5.46, 5.98, and 6.28 times under relatively optimal process parameters, which is mainly due to the improved surface integrity of the specimen after SAWJP treatment. However, the fatigue life of specimens treated with improper process parameters is decreased by 0.55 to 0.69 times owing to the terrible surface roughness caused by the material erosion. This work verifies that SAWJP can effectively improve the surface integrity and fatigue life of workpieces, and reveals the relationship between process parameters, surface integrity, and fatigue life, which provides support for the promotion of SAWJP in the manufacturing fields.