Background: Environmental tobacco smoke (ETS) has been linked to behavioral problems, but no study has assessed its relationship with dental anxiety. Therefore, this study’s goal is to assess the relation between ETS and both behavioral problems and dental anxiety among children. Methods: The study sample was collected from two centres in Jeddah from October 2019 to January 2020. Inclusion criteria included healthy 5–16-year-old children having their first dental visit with no emergency complaint. The questionnaire including general information, ETS exposure, the child’s anxiety using the Abeer Children Dental Anxiety Scale (ACDAS) and dental behavior using the Frankl Behavioral Rating Scale. Results: Of 500 children, 337 (67.4% response rate) responded to the questionnaire, among whom 201 (59.6%) had been exposed to passive smoking compared to 136 (40.4%) who had not. Exposed children had a statistically significantly greater tendency to develop anxiety (p = 0.002) and demonstrate uncooperative behavior (p = 0.006). Generalized linear mode and binary regression analyses suggested that ETS has a statistically significant effect on children’s dental anxiety and behavior (p < 0.05). Conclusions: Children exposed to ETS demonstrated statistically significantly higher anxiety levels and uncooperative behavior in the dental clinic compared to those who were not exposed.