Structurally reconfigurable RNA structures enable dynamic transitions of the functional states in response to diverse molecular stimuli, which are fundamental in genetic and epigenetic regulations. Inspired by nature, rationally designed RNA structures with responsively reconfigurable motifs have been developed to serve as switchable components for building engineered nanomachines, which hold promise in synthetic biological applications. In this review, we summarize recent progress in the design, synthesis, and integration of engineered reconfigurable RNA structures for nanomachines. We highlight recent examples of their targeted applications such as biocomputing and smart theranostics. We also discuss their advantages, challenges as well as possible solutions. We further provide an outlook of their potential in future synthetic biology.