Based on data from the 2020 China Longitudinal Aging Social Survey (CLASS), this study empirically examines the impact of digital network use on the mental health of older adults, and conducts heterogeneity analysis and mechanism tests. The results show that digital network use reduces depressive mood scores among older adults and improves their episodic memory and mental status scores. This finding remains valid after addressing endogeneity and conducting robustness tests. Heterogeneity analysis indicates that the positive effect of digital network use on mental health is more significant among older adults aged 70 and above, those who do not live alone, and those with a certain level of self-care ability. In addition, different types of digital network use have varying effects on the mental health of older adults. Personal attitudes toward aging and the level of social adaptation moderate the relationship between digital network use and the mental health of older adults. The findings suggest that efforts should be made to improve the digital literacy of older adults, promote the digital inclusion of the marginalized older population, and emphasize the positive effects of digital networks on the mental health of older adults.