A convenient and highly α-regioselective strategy for the synthesis of 3-prenyl-3-hydroxy-2-oxindoles has been developed starting from isatins and prenylzinc with good to excellent yields. This protocol provides a straightforward and practical way to introduce an α-prenyl moiety into the C-3 position of isatins. The advantages of this reaction are use of the cheap and readily available reagents, operational simplicity, and wide substrate scope. Furthermore, this transformation was applied to the synthesis of several oxindole-containing natural products, which further demonstrated the synthetic utility of this methodology.