Solution-processed organic-inorganic hybrid halide perovskite has emerged as an excellent material for harnessing solar energy. The ease of processing offers a fairly straightforward approach to integrate methylammonium lead iodide perovskite with diverse technological platforms. Metamaterials, with an array of artificially designed meta-atoms and extraordinary electromagnetic properties, have enabled several functionalities in the passive mode, especially for flexible photonic devices, which have found application in the areas of flexible displays and wearable sensors. However, it is extremely challenging to induce a dynamic response in flexible photonic devices. Here, we experimentally demonstrate that the solution-processed perovskite with an intrinsic ultrafast response could be an ideal platform for developing active flexible photonic devices. A thin perovskite layer on a flexible metadevice enables an ultrafast all-optical switching of Fano resonance with a time constant of 500 ps. The hybrid flexible metaphotonic device reveals an ultrasensitive dynamic switching with a deep-subwavelength thin film (λ/10 000) of perovskite at extremely low fluence of photoexcitation. The low-cost, facile processing, ultrafast, and highly photosensitive nature of the flexible metaphotonic device could find important applications in high-speed data encoding, flexible displays, wearable optoelectronics, and ultrasensitive photodetectors. Our findings provide a new platform for ultrafast flexible photonic devices fueled by the remarkable photoconductivity of methylammonium lead halide perovskite. © 2017 American Chemical Society.