Structural health monitoring (SHM) of civil engineering infrastructure, especially of bridges, has played a vital role in ensuring the safety as well as the integrity of the whole structure. SHM system enables inspectors to detect structural damage while it is still at its primal stage, thus reduces significantly the maintenance cost of the structure. Many researchers have focused on applying optimization techniques to improve the effectiveness of damage detection tool, especially those of natural-inspired algorithms. In this paper, we introduce an application of slime mould algorithm (SMA)—a novel metaheuristic optimization algorithm to solve the damage detection problem of a suspension footbridge. The highly accurate result shows that SMA is effective not only in detecting but also in localizing damages on the bridge.