In this work, we present a general photoredoxcatalyzed method for the radical group transfer of vinyl and alkynyl silanes. Using activated as well as unactivated alkyl iodides as radical precursors, we demonstrate the installation of alkenes and alkynes on sp carbon atoms across a broad range of substrates. Our protocol exhibits excellent functional group tolerance, and enables the removal of the siloxane tether without requiring the use of a fluoride source. Mechanistic investigations, moreover, reveal the importance of silicon in driving the group transfer reaction. We expect this indepth understanding to facilitate future use of vinyl and alkynyl silanes in radical chemistry.