This study investigates the use of Carbon Fiber (CF) sheets bonded to out-of-plane gusset welded joints with initial fatigue cracks using the Vacuum Assisted Resin Transfer Molding (VaRTM) technique for crack repair. The research aims to evaluate the effectiveness of this repair method in inhibiting fatigue crack propagation and enhancing the fatigue resistance of welded joints. Bending fatigue tests were performed on specimens repaired with CF sheets, and the results were compared with non-repaired joints. The number of CF sheet layers required for suppressing crack growth was calculated based on the stress intensity factor range, ensuring it remained below the threshold for crack arrest. Additionally, a step design was implemented to prevent debonding at the edges of the CF sheets, thereby improving the durability of the repair. The test specimens, with varying repair coverage, demonstrated significant improvements in fatigue life. Specifically, the repaired specimens showed no crack propagation at lower stress ranges and reached fatigue limits of over 10 million cycles without debonding. At higher stress ranges, debonding occurred but was limited to the edges, with the step design effectively mitigating this failure mode. The results confirm that the CF sheet bonding technique via VaRTM not only delays crack propagation but also provides the potential for complete fatigue crack arrest. This repair method offers a promising solution for extending the life of aging steel structures, such as bridges, by enhancing their fatigue durability and minimizing the risk of failure due to fatigue-induced damage.