Despite the ample evidence pointing to a strong dependence, the interplay between chemical ordering and shape of large ( >100 atoms) particles remains unclear and is inaccessible by current computational structure prediction approaches. For example, shapes derived from the Wulff construction assume the preservation of bulk chemical ordering, and the aforementioned single-and fixed-shape approaches are limited by design. To address this, we have developed a novel and efficient global optimization approach exploiting energy decomposition into atomic contributions to evaluate both chemical ordering and shape in bimetallic NPs. We showcase this approach by studying technologically relevant PtAu nanoalloys, for which we demonstrate that intricate shape transitions occur as a function of the relative Pt:Au concentration.