Purpose It was aimed to examine smartphone addiction and loneliness among high school students. Design and Method This descriptive and cross-sectional research was implemented with 1185 high school students. Data collection tools were "Smartphone Addiction Scale-Short Version," "UCLA Loneliness Scale," and "Parental Attitude Scale." Findings As the level of addiction to smartphones rose, the percentage of students feeling lonely dropped (p < .001). Although the students' smartphone addiction was low, the rate of using the smartphone to be relieved of loneliness and for the purpose of the communication was high. Practice Implications Education programs for improving the communication skills of adolescents that may be instrumental in reducing loneliness would in fact be effective in terms of smartphone usage and feelings of loneliness.