We demonstrate the accuracy of the hybrid functional HSE06 for computing band offsets of semiconductor alloy heterostructures. The highlight of this study is the computation of conduction band offsets with a reliability that has eluded standard density functional theory. A high-quality special quasirandom structure models an infinite random pseudobinary alloy for constructing heterostructures along the (001) growth direction. Our excellent results for a variety of heterostructures establish HSE06s relevance to band engineering of high-performance electrical and optoelectronic devices.