A highly atom-economical allylation of oxindoles with vinyl cyclopropanes catalyzed by Pd(PPh₃)₄ has been developed, setting up a practical venue for the installation of an all-carbon quaternary center at the 3-position in oxindoles under mild reaction conditions. Importantly, the reaction proceeded well without any additives and no waste was produced, affording linear products with high regioselectivities (>20:1). Enantioselective allylic alkylation has also been realized to provide the desired products in good yields and 35% ee.