Optimizing truss structures is essential in civil engineering, aiming to reduce weight and support sustainable, high-efficiency designs. In this study, the Portia spider algorithm (PSA) is introduced as a novel optimization algorithm specifically designed for truss design problems with sizing constraints and continuous variables. PSA integrates advanced solution modification strategies to effectively address the inherent complexity of truss structure optimization. The algorithm’s performance was thoroughly evaluated through extensive testing on 25-bar truss structures. The findings indicate that PSA consistently yields superior truss designs compared to other swarm-based techniques, achieving significant weight reductions and enhanced design quality. By offering a robust and computationally efficient solution for truss optimization, PSA demonstrates considerable potential to advance the field of structural optimization. These results highlight PSA as a valuable resource for civil engineers seeking to improve structural performance and efficiency, ultimately contributing to more sustainable construction systems.