The crystal of the title compound, C9H20N+·C9H21O3SSi−, is built of aggregates, each made up of two 2,2,6,6-tetramethylpiperidinium cations and two triisopropoxysilanethiolate anions. The aggregates are linked by four N—H⋯S bonds and correspond to an R
2
4(8) graph-set motif.