The structural resistance of rectangular hollow section (RHS) tubular joints reinforced with longitudinal passing-through plates — applied within the context of a steel Warren truss girder for a pedestrian bridge and fabricated using laser cutting technology (LCT) — is investigated. Two full-scale reinforced joint designs were experimentally tested and compared with a conventional welded RHS truss structure. Finite element modelling, supported by geometrically and materially nonlinear analysis with imperfections (GMNIA), was employed to calibrate the numerical models and to extend the investigation of the reinforced solutions incorporating passing-through stiffening plates. A parametric study was conducted to evaluate the influence of key design parameters, including the thickness and diameter of the chord member, the gap between diagonals in a K-type joint, the axial load level in the chord, and the ratio of axial force in the chord to that in the brace members. The results indicate that the implementation of passing-through stiffening plates in RHS joints, when combined with adequate geometric detailing and welding procedures, can enable the joint resistance to reach the plastic resistance of either the chord or the diagonals. The proposed LCT-based reinforcement approach demonstrates significant potential for enhancing both the structural performance and fabrication efficiency of RHS tubular truss girders. This work is part of the EU-RFCS-101034038 funded research project LASTTS - Laser Cutting Technology for Tubular Structures.