In recent years, platinum-based single crystalline nanoalloys as nanoscale catalysts, such as Pt-M (M = Ni, Co, Fe..etc.), have exhibited improved catalytic performance due to the increase in the surface-to-volume ratio. Some Pt-M nanopolyhedra such as nanocubes and nano-octahedra have been reported with enhanced activity when being used as electrocatalysts. In order to further establish a correlation between the exposed nanocrystal facets (shapes) and their corresponding activities, a pursuit of shape-controlled nanocatalyst synthesis is essential. Although PtPb nanoalloys have been prepared using solution-based methods, few studies have highlighted their catalytic activity as a function of the nanocrystal shape. This work focuses on a modified polyol synthesis technique and an adjustment of the Pb-metal precursor, which serves as a “buffer” in the nucleation stage of the shape-controlled nanoalloy development. Using this developed synthetic strategy, shape-controlled hexagonally close-packed PtPb nanoalloys can be prepared in a one-pot synthesis without additional post-treatment. The as-prepared PtPb nanocrystals demonstrate an improved anode electrocatalytic performance.