A large proportion of youth believe that the world of cyberspace provides them with a relatively safe and anonymous digital bubble ripe for uninhibited self-expression. At the same time, observers have noted an increase of individuals behaving in an unrestrained manner on the Internet, while researchers have reported elevated rates of cyber aggressive behavior. What remains unclear, however, is whether, and how, disinhibition might be related to cyber aggression. In an aim to explore the possible associations, a large sample (total N = 709) of high school (M age = 15.56 years) respondents from New Zealand were recruited, and completed a survey featuring scales assessing personality and technology behaviors, attitudes, habits, and trends. The present study was designed to investigate whether the three dark personality traits of narcissism, psychopathy, and sadism would predict false self perceptions, and in sequence, online disinhibition and aggressive online behavior. All three dark personality traits, as well as false self, were positively associated with online disinhibition. Perceptions of false self were found to be a significant predictor of cyber aggression when mediated by online disinhibition. In the case of cyber aggression, however, psychopathy, sadistic traits, and online disinhibition were found to be significant predictors of this outcome. The results collectively provide a more nuanced understanding of how antisocial personality traits are associated with maladaptive identity formation (i.e., endorsement of false self beliefs) as well as maladaptive online behavior.