Rapid social development has made the elderly increasingly dependent on mobile phones, and mobile phone addiction has a negative effect on sleep quality. The underlying mechanism between the two is unclear. This study examined the mediating role of depression and loneliness in the relationship between phone addiction and sleep quality in older adults. Mobile Phone Addiction Scale Short Version, Pittsburgh Sleep Quality Index scale, UCLA (University of California, Los Angeles)-8 Loneliness Scale, and Short Geriatric Depression Scale (GDS-15) were used to investigate 459 older adults in China. The results showed that there was a positive correlation between mobile phone addiction and sleep quality in the elderly. In addition, depression and loneliness partially mediated the relationship between mobile phone addiction and sleep quality in older adults. The current study provides new insights into the impact of mobile phone addiction on sleep quality and the importance of depression and loneliness in older adults. The limitations and significance of this study are discussed.