In South Korea, suicide is the fourth leading cause of death, which is the highest rank among the Organization for Economic Cooperation and Development countries. Suicidal behaviors have shown a significant association with addiction, including internet abuse and dependence in South Korea. Internet addiction is characterized by excessive or poorly controlled preoccupations, urges, or behaviors regarding computer use and internet access. Therefore, we overviewed the relationship of internet addiction and suicidal behaviors in this article. The relationship between internet addiction and suicide was confirmed. The first is the biological approach related to reward systems, cognitive function, brain neurotransmitters, and gene expression. The second is the psychopathological approach associated with depression, anxiety, impulse control, and substance-related disorders including diseases such comorbidities. Finally, the third is the socio-environmental approach related to the contextual stimuli and social isolation and alienation caused by the lack of support and low self-esteem. In conclusion, internet addiction is significantly associated with suicidal behaviors. Internet addiction is a medical condition which is treatable and preventable, and suicide behaviors caused by internet addiction can be controlled through early diagnosis and treatment. Based on a growing body of research on the cause and effect relationship of internet addiction and suicide, various interventions of protection and prevention have been studied.