Photo-fabrication of surface-wrinkled hybrid organic-inorganic composite films containing TiO2 nanoparticles stabilized with CTA(+) and PVP allows the preparation of tunable hierarchical structures with environmentally responsive properties. With changes in relative humidity, the film swells by absorbing water and smooths out the wrinkles at the micrometer scale; this response is reversible and wet-dry cycles can be run.