Lightweight steel geodesic domes are widely used in public structures and often support suspended equipment, which can affect their seismic performance. Understanding how such additional masses influence dynamic response is essential for safe design. In this paper, six steel geodesic dome models, shaped by two mesh topology methods, were numerically analyzed and subjected to three seismic excitations using DIANA FEA. Also, this paper evaluates displacements and accelerations for configurations without suspended mass, with mass at the dome center, and with mass offset by 10 meters. Results indicate that the dome topology significantly affects seismic response, and even small suspended masses (about 3.5–4.6% of the dome weight) can notably increase maximum displacements and accelerations, especially when centrally located. These findings suggest that both the structural topology and the placement of additional masses should be carefully considered in the seismic design of geodesic domes to ensure structural integrity under earthquake loading.