<p>This study examined the fatigue crack growth (FCG) behavior of STS316L stainless steel with inherent compressive residual stress induced by shot peening. First, an analytical Almen intensity of 0.344 mmA was derived through a discrete–finite element (DE-FE)-based multi-impact shot peening simulation, which showed a relative error of only 0.29% compared to the experimentally measured Almen intensity of 0.343 mmA. This analytically derived effective Almen intensity (0.344 mmA) was then applied to a unit-cell model to obtain multi-node area-averaged residual stress fields. Subsequently, FCG analyses and experiments were conducted under shot peening (SP) and non-peening (NP) conditions, and the fatigue life was compared for the same crack length. The observed error between simulation and experiment was 4%, confirming that the proposed numerical approach incorporating residual stress (area-integration-based peening residual stress) is highly effective and accurate. Furthermore, both experimental and analytical results consistently showed that SP specimens exhibited longer fatigue life than NP specimens at the same crack length. Specifically, at applied loads of 3 kN, 4 kN, and 5 kN, the fatigue life of the SP specimens was approximately 5.81%, 12.00%, and 3.99% higher than that of the NP specimens in experimental results and 2.50%, 11.84%, and 4.33% higher, respectively, in numerical analysis. Fractographic analysis further revealed that SP specimens exhibited consistently larger crack propagation angles than NP specimens. At an applied load of 3 kN, for example, the crack propagation angle reached 60° in SP specimens compared to 50° in NP specimens, indicating that compressive residual stress redirected crack growth more strongly toward the surface and thereby contributed to growth retardation. Ultimately, the FCG analysis model incorporating multi-node-averaged peening residual stress proposed in this study will be highly useful for predicting the actual growth behavior of fatigue cracks.</p>