Pt(100) facet is generally considered less active for the oxygen reduction reaction (ORR). Herein, we report a unique Pt branched structure – multicube whose surface is mostly enclosed by {100} facets but contains high-index facets in the small junction area between the adjacent cubic components. The synthesis is accomplished via a Ni2+-mediated facet evolution from high-index {311} to {100} facets on the frameworks of multipods. Despite the high {100} facet coverage, the Pt multicubes exhibit impressive ORR activity in terms of half-wave potential and current density nearly to the level of the most active Pt-based catalysts, while the durability of catalysts is well retained. The facet evolution creates a set of samples with tunable ratios of high-index to low index facets. Our results reveal that the excellent ORR performance of Pt multicubes is a combined result of active sites by high-index facets and low resistance by flat surface. It is anticipated that this work will offer a new approach to facet-controlled synthesis and ORR catalysts design.