Abstract: High-strength steel T-joints are widely used in the load-bearing components of critical engineering equipment such as ships, offshore platforms, and rail transit. When serving under complex loading conditions, their mechanical properties and fracture behavior are directly related to structural safety. BS960 high-strength steel T-joints were fabricated using the flux-belt constrained arc welding (FBCA) method. For two typical working conditions of static tensile and dynamic impact, high-speed digital image correlation (DIC) tests, fracture observations, and EBSD characterizations were conducted, and the fracture mechanisms of the T-joints under different loading conditions were analyzed. The results indicate that under static loading, the strain distribution of the joint is relatively uniform, exhibiting ductile fracture characteristics; under dynamic impact, the strain is significantly concentrated at the weld root (i.e., the intersection between the horizontal and vertical plates), exhibiting obvious crack initiation and accelerated propagation characteristics, and presenting a mixed ductile–brittle fracture mode. This study reveals the fracture laws of FBCA-welded BS960 high-strength steel T-joints under different loading conditions, providing experimental evidence and theoretical support for the safe service of high-strength steel welded structures under different working conditions.