Abstract Nanoimprinting lithography (NIL) technique is widely utilized for nanostructure engineering of soft materials. Owing to the soft organic/inorganic hybrid nature, the optical and crystallographic properties of halide perovskites (HPs) are improved by the NIL process. However, the wide application of NIL into various HPs has lagged. Herein, a defect‐free nanopatterned‐(FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 (NP‐FAMA) film is successfully developed via optimized NIL. As surface energy is a key parameter to be controlled for accomplishing NIL process, trichloro(1H,1H,2H,2H‐perfluorooctyl)silane (CF 3 (CF 2 ) 5 CH 2 CH 2 SiCl 3 ) treatment on polymeric mold, which prevents the peeling‐off problem. Along with surface morphology modification, NP‐FAMA exhibits enhanced crystallographic and photophysical properties. The photoresponsivity of NP‐FAMA‐based photodetectors outperforms bare (b‐) FAMA‐based devices. Surprisingly, the external quantum efficiency (EQE) of the NP‐FAMA‐based devices dramatically increases to 225%, photomultiplication (PM), under 1 nW illumination without any charge‐injecting materials. To clarify these PM phenomena, the trap‐assisted PM mechanism is suggested as a model system for promoting photocurrent generation of HPs that is supported by PL analysis.