RhI(PPh3)3 or [RhI(cod)]2 (cod = 1,5-cyclooctadiene) as a catalyst delivers both (Z)- and (E)-alkenylsilanes in the stereodivergent hydrosilylation of terminal alkynes with heteroatom-substituted organosilane reagents. Treatment of the rhodium catalyst and the silane reagent followed by addition of terminal alkyne at room temperature leads to (Z)-silanes, while addition of the silane and the alkyne to the rhodium catalyst in one portion and heating at 60 °C affords (E)-silanes highly selectively. The obtained (E)- and (Z)-alkenylsilanes bearing heteroatom substituents on the silicon atom are subjected to the palladium-catalyzed cross-coupling reaction with aryl halides to form a carbon−carbon bond with retention of stereochemistry. The stereodivergent hydrosilylations are applied to the polyaddition with bifunctional alkynes (1,3- and 1,4-diethynylbenzene) and silanes (1,3- or 1,4-bis(dimethylsilyl)benzene), giving silicon-containing polymers, poly(aryleneethenylenesilylene)s, in highly stereocontrolled m...