Scarf patch repair is widely adopted for the restoration of damaged wind turbine blades due to its load transfer capability, aerodynamic smoothness, and minimal stress concentration. The recent introduction of UV-curable resin systems has further enhanced the practicality of on-site composite repairs by enabling rapid curing at ambient conditions and reduced downtime. These advantages make UV-curing–based scarf repairs particularly attractive for large-scale wind energy structures, where accessibility and repair time are critical constraints. However, the curing process induces residual stresses in the repaired region due to resin shrinkage and viscoelastic effects, which can influence the structural performance and fatigue life of the repair. In the present work, the effect of cure-induced residual stresses on the fatigue life of UV-cured scarf patch repairs is investigated using a combined experimental and computational approach. A cure-dependent viscoelastic material model is implemented in a finite element framework to simulate the UV-curing process and predict the evolution of residual stresses in the repaired laminate. The predicted residual stress state is subsequently incorporated into a fatigue damage model to evaluate the life of the repaired structure under cyclic loading. Experimental fatigue tests are performed on composite specimens repaired using UV-curing based scarf patches to validate the numerical predictions. The comparison between numerical and experimental results shows good agreement, highlighting the importance of accounting for residual stresses in fatigue life prediction. The proposed framework provides a practical and reliable approach for assessing the durability of UV-cured scarf patch repairs and can assist in improving repair design and life estimation for wind turbine blades.