Problematic online betting among adolescents has attracted considerable public attention internationally for the last two decades. Although the online betting prevalence rate in Turkey is unclear, some reports indicate that it could be more pervasive than is currently estimated. The aim of this study was to determine the prevalence of problematic online betting, common behaviors of youth related to betting, and to identify the effect of family on online betting among Turkish adolescents. We surveyed 6116 adolescents aged between 12 and 18 in Istanbul to determine if they are problematic Internet users for betting. Although 756 (12.4%) adolescents reported that they play online betting, only 176 adolescents (2.9%) were classified as problematic Internet users. Thus, we collected further data from those 176 adolescents, 14.8% of which were female. A significant positive correlation was found between Internet Addiction (IA) and duration of betting. Almost 61% of participants expressed that they prefer to be online because they do not have better things to do. Almost a quarter of the participants started online betting between 10 and 12 years of age. All participants know someone who bets online. In terms of frequency, these are friends, relatives, siblings, and parents, respectively. Although there is no relationship between family structure and IA among adolescents who are problematic users, participants who live in an unstable family have higher IA scores than participants who live in a stable family.