BACKGROUND: This study explores the relationship between smartphone addiction and sleep quality, and to further assess the mediating role of loneliness and depression. METHODS: A survey of 200 older adults individuals was conducted using the Smartphone Addiction Scale-Short Version (SAS-SV) for smartphone addiction, Pittsburgh Sleep Quality Index (PSQI) for sleep quality, Geriatric Depression Scale-15 (GDS-15) for depression, and DeJong Gierveld Loneliness Scale (DGLS) for loneliness. Linear regression and mediation analysis were performed for statistical analysis. RESULTS: A negative causal relationship was observed between smartphone addiction and sleep quality in the older adults (p < 0.05). Depression and loneliness in the older adults may potentially exacerbate the effect of smartphone addiction on sleep quality (p < 0.05). CONCLUSION: Individuals with smartphone addiction appeared to have poorer sleep quality, psychological factors play a mediating role in the association between smartphone addiction and sleep quality in the older adults. This emphasizes the importance of care for the mental health of the older adults and recognizes the negative impact of smartphone addiction on their quality of life.