Insulating bulk and conducting edge states makes 2D topological insulators (TI) a candidate quantum material with varied applications. 2D binary monolayers composed of group-11 transition metals and halides with puckered structures have been recently explored for their photocatalytic and quantum cutting properties. However, such binary systems have not yet been explored for their topological properties. Herein, the topological and catalytic properties of one such binary compound, gold iodide (AuI) which belongs to P6 ₃/mmc [194] space group governed by a honeycomb lattice structure is explored. The nontrivial TI nature exists in a narrow window of strain from −2% to 4%. Within this region, by employing strain engineering technique the bandgap can be tuned to as high as 0.113 eV. The nontrivial character is further investigated by calculating the ${\mathbb{Z}}_2$ invariant, robust edge state spectra and slab band structures. The Gibbs free energy towards hydrogen evolution reaction is computed to assess the catalytic property of AuI. The Gibbs free energy was found to be −0.40 eV with Volmer–Heyrovsky as the preferred reaction mechanism. With this study, it is proposed AuI monolayer as a candidate material for prospective applications in the field of nanoelectronics and catalysis.