A Cu-catalyzed carbonylative silylation of unactivated alkyl halides has been developed, enabling efficient synthesis of alkyl-substituted acylsilanes in high yield. A variety of functional groups are tolerated under the mild reaction conditions, and primary, secondary, and tertiary alkyl halides are all applicable. The practical utility of this method has been demonstrated in the synthesis of acylsilanes bearing different silyl groups as well as in situ reduction of a product to the corresponding alpha-hydroxylsilane in one pot. Mechanistic experiments indicate that a silylcopper intermediate activates alkyl halides by single electron transfer to form alkyl radical intermediates and that carbon-halogen bond cleavage is not involved in the rate-determining step.