We report block copolymer assisted synthesis of a Au metal core coated with a nanodendritic Pt shell (Au@Pt). Herein, a rapid, one-step and efficient wet-chemical route is proposed to straightforwardly synthesize Au@Pt with high yield (approximately 100%), which was mediated by Pluronic F127 block copolymer from the reduction of Pt and Au complexes by ascorbic acid (AA).