The asymmetric distribution of lipids on the inner and outer membranes of a cell plays a pivotal role in the physiological and immunological activities of life. It has inspired the elaboration of synthetic asymmetric vesicles for the discovery of advanced materials and functions. The asymmetric vesicles were generally prepared by amphiphilic block copolymers. We herein report on the formation of asymmetric vesicles self-assembled by amphiphilic sequence-controlled polymers with two hydrophilic segments SU and TEO. We also developed an efficient fluorescence titration method with europium(III) ions (Eu3+) to determine the uneven distribution of SU and TEO. SU units are preferentially located on the outer membrane and TEO on the inner membrane of the resulting vesicles, which is facilitated by the electrostatic repulsion of SU and the U-shaped folding of the hydrophobic backbone of the resulting polymers. This work shows that sequence-controlled polymers with alternating monomer sequence provide a powerful toolbox for the elaboration of important yet challenging self-assembled structures for emerging functions and properties.