This study was conducted to identify the opportunities and threats posed by the Internet and its effects on the psychological well-being of online children and adolescents. This qualitative research had a synthesis design based on Roberts’ six-step research synthesis model. The statistical population of the study was comprised of all national and international research and scientific articles related to the research topic in the period of 2000-2021. 250 of such sources which were collected from various databases were reviewed and analyzed based on the research input criteria. The results of the study revealed that online children and adolescents have opportunities such as socialization and communication with others, self-expression and identity formation, learning and development of creativity, personal growth and self-acceptance and threats such as anxiety and depression, sleep disorder, low self-esteem, social isolation, lack of self-acceptance, Internet addiction, academic failure, cyberbullying, suicide and sexual abuse, each of which can affect their psychological well-being.