Abstract: In this work, the microstructure and early-stage localized corrosion behavior of AA2024 aluminum alloy fabricated through additive friction stir deposition (AFSD) were systematically characterized. The AFSD process achieved significant grain refinement and effective fragmentation of brittle constituent phases within the alloy. In contrast, micrometer-scale S-phase remained relatively intact without fracture and primarily underwent plastic deformation, especially on the lateral surface. Attributing to more sufficient dynamic recrystallization, the grain size at the interfacial region between adjacent deposition layers was further refined. The thermal input generated during AFSD induced precipitate S-phase coarsening, which was more pronounced on the lateral surface. These coarsened precipitates act as additional active sites for pitting initiation. Notably, the top and lateral surfaces of AFSD made component exhibited comparable corrosion performance. AFSD effectively improved the microstructure homogeneity of AA2024 and lowered the likelihood for stable pit initiation derived from the synergistic effect of clustered particles.