["Asian-Pacific Economic Literature, EarlyView. ", "\nABSTRACT\nThis study examines whether working‐hour trends differed across Korean industries with varying levels of AI exposure following the diffusion of AI technologies that accelerated in 2022. While a growing body of research has examined the effects of AI on productivity, employment and wages, relatively little attention has been paid to working hours. To address this gap, this study constructs a Korean AI Industry Exposure Index. Using an exposure‐based event‐study framework, the analysis estimates differential working‐hour trends across industries between 2020 and 2025. The results show that industries with higher levels of AI exposure experienced larger declines in weekly working hours in 2023, 2024 and 2025. Moreover, the magnitude of the negative association grows over time, reaching its largest value in 2025. In contrast, no statistically significant differences are observed in 2020 and 2021, consistent with the parallel‐trends assumption. Additional analyses reveal no statistically significant heterogeneity by employment type, flexible working arrangements, labour union membership or part‐time employment status. Overall, the findings suggest that the diffusion of AI technologies after 2022 was associated with progressively larger reductions in working hours in highly AI‐exposed industries.\n"]