The first iron-catalyzed 1,2-difunctionalization of styrenes and conjugated alkenes with silanes and either N or C, using an oxidative radical strategy, is described. Employing FeCl and di-tert-butyl peroxide allows divergent alkene 1,2-difunctionalizations, including 1,2-aminosilylation, 1,2-arylsilylation, and 1,2-alkylsilylation, which rely on a wide range of nucleophiles, namely, amines, amides, indoles, pyrroles, and 1,3-dicarbonyls, thus providing a powerful platform for producing diverse silicon-containing alkanes.