Phubbing behavior is a phenomenon that consists in ignoring people in situations of social interaction whilst paying attention to one's smartphone. The study of this behavior enables reflection on the development of healthy behavior patterns when using technology and the design of intervention strategies to cope with phubbing behavior. This study aimed to investigate the relationship between phubbing behavior, use of Instagram, personality traits (Big Five), and sociodemographic variables (gender, education, and age) among Brazilian adults. This was a cross-sectional study with a sample of 1551 adults (61.7% women; 29.9% men), aged between 18 and 76 years (M = 31.6 years; SD = 9.6 years). The results of the correlation analysis indicated that excessive use of Instagram showed a high, positive association ρ (1551) = 0.442 with Phubbing Behavior and a moderate one with neuroticism ρ (1551) = 0.272. Phubbing behavior was positively and moderately with neuroticism ρ (1551) = 0.290, but it had a weak, negative correlation with age ρ (1551) = -0.117; p < 0.001. Multiple linear regression analysis (forward method) indicated that the variables that most strongly impacted Phubbing Behavior were neuroticism (ΔR2 = .236), conscientiousness (ΔR2 = .244) and use of Instagram (ΔR2 = .204). This result indicates that conscientiousness may have a predictive potential to decrease phubbing behavior, whereas neuroticism and use of Instagram may lead to increased phubbing. Multivariate Analysis of Variance indicated that excessive use of Instagram registered higher scores for women (M = 11.48; SD = 0.21) than for men (M = 9.45; SD = 0.27, p < 0.001). It was concluded that while conscientiousness can function as a protective factor for the development of phubbing behavior, high levels of neuroticism and excessive use of Instagram have greater potential to act as risk factors for it. In addition, neuroticism is also a risk factor for excessive use of Instagram, and women are more prone to such overuse.