This study proposes a novel method to prevent fatigue cracks at the root of fillet welds in steel bridge supports by inserting epoxy resin as an adhesive material. A total of 36 specimens, categorized into welded‐only and bonding‐assisted types, were subjected to a series of four‐point bending fatigue tests to simulate cyclic tensile stress conditions. Additionally, finite element analysis was employed to investigate the impact of epoxy insertion on stress distribution near the weld root. The results demonstrated that bonding‐assisted specimens exhibited significantly improved fatigue life compared to welded‐only specimens, with a notable reduction in tensile stress at the weld root. Furthermore, a displacement‐based method was employed to evaluate weld root fatigue performance, yielding consistent results. These findings highlight the potential of integrating adhesive bonding in fillet welds to improve the durability and service life of steel bridge structures by effectively mitigating fatigue‐related issues.