An organocatalytic asymmetric allylation of 3-indolylmethanol has been established via hydrogen-bond activating mode, which directly assembles isatin-derived 3-indolylmethanols and o-hydroxystyrenes into chiral allyl-substituted oxindoles with one all-carbon quaternary stereogenic center and one newly formed C=C bond in excellent enantioselectivity and (Z)-selectivity (up to 97% ee, >20 : 1 Z/E ratio). This transformation provides an efficient strategy for asymmetric C3-functionalization of indoles and allylation of 3-indolylmethanols with precise control of the stereoselectivity in the formation of C-C and C=C bonds.