The majority of research on self‐monitoring has focused on the positive aspects of this personality trait. The goal of the present research was to shed some light on the potential negative side of self‐monitoring and resulting consequences in two independent studies. Study 1 demonstrated that, in addition to being higher on Extraversion, high self‐monitors are also more likely to be low on Honesty‐Humility, which is characterized by a tendency to be dishonest and driven by self‐gain. Study 2 was designed to investigate the consequences of this dishonest side of self‐monitoring using two previously unexamined outcomes: moral disengagement and unethical business decision making. Results showed that high self‐monitors are more likely to engage in unethical business decision making and that this relationship is mediated by the propensity to engage in moral disengagement. In addition, these negative effects of self‐monitoring were found to be due to its low Honesty‐Humility aspect, rather than its high Extraversion side. Further investigation showed similar effects for the Other‐Directedness and Acting (but not Extraversion) self‐monitoring subscales. These findings provide valuable insight into previously unexamined negative consequences of self‐monitoring and suggest important directions for future research on self‐monitoring. Copyright © 2013 John Wiley & Sons, Ltd.