The formation of dissolved gaseous mercury (DGM) in lake water is mainly attributed to photochemical processes mediated by dissolved organic matter (DOM). In this study, we explored how different DOM components influence the Hg(II) photoreduction rate constant (k_r) in lake surface water. For this purpose, the k_r and the fluorescence properties of DOM were obtained from three Korean lakes with different trophic states. Three major fluorophores were identified by excitation-emission matrix fluorescence spectroscopy combined with a parallel factor analysis: plant-derived terrigenous humic-like DOM (C1), autochthonous DOM (C2), and soil fulvic-like DOM (C3). The principal component analysis (PCA) loading matrix demonstrated that k_r increases when bulk DOM has high flavin-like and soil-derived fulvic-like fractions. The results of a Pearson’s correlation agreed with the outcome of the PCA analysis: k_r showed a strong positive correlation with the soil fulvic-like DOM component (r = 0.92) and the redox index (r = 0.92). This was further confirmed by a partial least squares-regression model that predicted k_r (r = 0.99) using multiple DOM components. Overall, our results suggest that k_r can be modeled using fluorescence intensities of diverse DOM components, which in turn has the potential to be incorporated into Hg biogeochemical models to better predict the variability of Hg redox rates across lake systems.