Abstract: Variable stiffness laminates manufactured by automated fiber placement (AFP) inevitably contain gaps and overlaps as typical process-induced defects. However, the effects of these defects on the impact resistance remain unclear, which limits the reliable strength prediction and engineering application of such composites in aerospace structures. In this study, low-velocity impact (LVI) and compression after impact (CAI) tests are conducted on variable stiffness unidirectional laminates with deliberately prefabricated gaps and overlaps to elucidate the quantitative effects of defect type and size on impact resistance and post-impact bearing capacity. It has been shown that overlap defects increase the peak load, impact stiffness, and CAI strength compared to defect-free laminates. This effect becomes more pronounced with increasing overlap size (a 2-mm overlap can increase the peak impact load by 9.2% and the residual compressive strength by 22.8%.). In contrast, gap defects consistently degrade the mechanical properties, accompanied by aggravated out-of-plane deformation and internal damage propagation (When the gap was 2 mm, the maximum out-of-plane displacement during impact increased by 6.5%, and the damage area increased by 110.1%.). Moreover, defect type significantly influences the buckling mode under CAI loading: defect-free and gap-containing specimens exhibit a W-shaped buckling pattern, whereas overlap-containing specimens show an S-shaped pattern. These findings indicate an asymmetric effect of gaps versus overlaps on impact performance and establish quantitative correlations between defect geometry and mechanical responses. Therefore, this study provides experimental data for damage tolerance assessment and process tolerance design in variable stiffness composites.