The geometries, stability, and electronic and magnetic properties of TbSi_{n} (*n*=2-13) clusters were systematically investigated using relativistic density functional theory (DFT) within the generalized gradient approximation. The average binding energies, dissociation energies, charge transfer, the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO) gaps, Mulliken populations (MP), and magnetic properties were calculated and were discussed. The TbSi_{n} (*n*=2-13) clusters do not form encapsulated structures at *n*=10. We conclude that the stability of TbSin is consistent with the encapsulated geometric structure and also with the inherent electronic stabilization. Furthermore, results of the calculated Mulliken populations show that the charge always transfers from Tb to Si. The magnetic moment is largely located on Tb and is mainly populated by *f*-block electrons. The *f* electrons are very localized and to a large extent not responsible for chemical bonding. The partial density of states (PDOS) of TbSi_{10} shows that there is strong sp hybridization between Tb and Si.