Responsive self-assembly is a general process in biological systems and is highly desired in engineered systems. DNA nanostructures provide a versatile molecular platform for studying such responsive self-assembly. Various triggers have been explored for DNA nanostructures. However, each trigger requires a unique mechanism for its response. This situation brings a great challenge to engineer the responsiveness. Herein, we propose an aptamer-based, allosteric mechanism for responsive DNA self-assembly. The aptamer-ligand binding causes the DNA motif to change its conformation and thus influences the motif assembly. With a model of an ATP aptamer, we have demonstrated the responsive assembly. Such responsive behavior, we believe, will be an important element for molecular machines, bioimaging/biosensing, and drug delivery.