A series of nanoflower-shaped X% Ir/MoS₂ catalysts with different Ir loadings were prepared based on a simple hydrothermal synthesis method and their catalytic activities in CO₂ hydrogenation were investigated. The Ir/MoS₂ catalyst has a nanoflower-like shape with a diameter of about 800 nm. The layers of two-dimensional nanosheets on the catalyst were well dispersed, which increased the exposure of the active sites. The doping of Ir could effectively tune the electronic structure of the catalyst, causing the local structure phase change of MoS₂. Under low reaction pressure, the 1% Ir/MoS₂ composite showed the highest formate selectivity (98%) and activity (8.6 mmol•g^–1•h^–1). The excessive Ir loading would lead to the agglomeration of Ir to form nanoparticles, which reduced the selectivity and activity of product. The 1% Ir/MoS₂ catalyst also showed excellent catalytic stability, and the catalytic activity did not decrease obviously after being reused three times. Based on control experiments, the catalytic mechanism and solvent effect were also studied and discussed. This study provid es a new way for developing high-performance catalysts for CO₂ hydrogenation to formate.