Smartphone addiction results in mental health disorders, especially among youth. Only a few studies are done among youth in rural areas. This study was conducted to find the association of anxiety, depression and stress in relation to smartphone addiction in rural undergraduate students. A cross-sectional survey was done among university students in the rural part of south India in 2018. 684 students from four different colleges participated in the study, and Depression Anxiety Stress Scale (DASS-21) and Smartphone Addiction Scale – Shorted version questionnaire (SAS-SV) scales were used. Descriptive analysis in terms of mean, standard deviation and categorical analysis as percentages and frequencies were applied. Overall 413 (60.4%) students were using smartphones, and the prevalence of smartphone addiction was around 26.8% and was found to be common among males than females (p<<0.001). Depression and stress were progressively greater with increasing usage across the three groups (p<<0.001). There was statistically significant weak positive correlation between the total depression (r=0.16; p<0.001), anxiety (r=0.10; p<0.05), and stress scores (r=0.24; p<0.001) with total addiction scores. Simple linear regression showed that with one unit increase in addiction scores there was a significant increase in depression (? = 0.156, p = 0.002), anxiety (?=0.098,p=0.046), and stress scores (?=0.236,p<0.001) and multiple linear regression showed stress was more significantly associated with addiction than depression and anxiety (B= 0.243; p<0.001). Alarming higher prevalence of depression, anxiety and stress among rural college students is a serious concern. Life skills education would address these growing public health problems.