In situ generated magnesium cyanide [NaCN/Mg(ClO4)2] is suggested as a convenient, readily available, non‐volatile and organic‐soluble reagent for hydrocyanation reactions. It was successfully used for nucleophilic cyanation of nitrosoalkenes, nitronates, as well as other typical π‐electrophiles, such as imines, α,β‐unsaturated ketones, alkylidenemalonates and azoalkenes.