Nanomachines capable of controlled programmable work at the nanoscale promise to revolutionize a vast range of research and eventually should impact on daily lives. Due to the ease of design and modification, DNA origami is emerging as a natural platform to build such machines. However, one essential challenge is the controlled and rapid actuation of DNA origami using an external biocompatible stimulus. Here, actuation based on temperature-induced phase transitions of the thermo-responsive polymer poly(N-isopropylacrylamide) (PNIPAM) is reported. By incorporating this polymer into DNA origami structures on either side of a flexible region, a “DNA origami flexor” is created that uses the tunable PNIPAM hydrophobicity to reversibly open and close the DNA structures. Such a mechanism has the advantage of being versatile and biocompatible, and possessing strong response to temperature changes of a few degrees Kelvin.