Abstract Exploring new haloplumbate hybrids and understanding the structure‐activity relationships are of great significance for further promoting their applications in the photovoltaic fields. Herein, with the in situ‐formed [Hmd] + (md = 2‐methyl‐1,3‐diazinane) templates, a new organic–inorganic hybrid iodoplumbate, namely [Hmd]PbI 3 ( 1 ), is successfully constructed and then structurally characterized using multiple technical approaches. X‐ray crystallography studies show that compound 1 features the typical 1D chain‐like motifs of [Pb 2 I 6 ] n 2 n − , generating the 3D supermolecular network by the extensive hydrogen bond interactions. Interestingly, compound 1 exhibits the semiconductive behavior, with an optical band gap of 2.72 eV. More attractively, the title compound has good photoelectric switching performances under the alternating light irradiation, whose photocurrent densities compete well with or surpass those of many metal halide counterparts. Further theoretical analyses reveal that the title compound has a more dispersive band structure (especially the value band) that facilitates the transport of charge carriers, which may be the main origin of its excellent optoelectronic performance. Presented in this paper also bring the studies of Hirshfeld surface, X‐ray photoelectron spectroscopy (XPS) as well as thermogravimetric analysis.