Revealing the relationships between geometric structure and electrochemical stability of Pt-based nanostructures is significant to catalyst development for the ethanol oxidation reaction (EOR) in an acidic media. Herein, we proposed the controllable construction of Pt x Bi y nanostructures with a continuous structural evolution by a simple colloidal synthesis. As the Bi feeding decreased, the inhibition effect of Bi 3+ on the epitaxial growth of Pt nanoparticles (NPs) was diminished, and Pt x Bi y nanostructures transformed from nanoparticle aggregates to nanodendrites, which induced the generation of PtBi−Bi 2 O 3 heterogeneous nanostructures by the electrochemical reactivation process. Benefiting from the modification of Bi species and nanodendrites, the optimal Pt 2 Bi 1 catalysts showed superior structural stability and catalytic durability with a high mass activity of 482.6 mA mg Pt −1 , which was 2.2 times that of commercial Pt/C. This work not only prepared a series of Pt-based heterogeneous nanostructures, but also provided an effective approach for high-performance EOR based on the structure− performance relationship.