Digit ratio (2D:4D) – a reliable marker of prenatal sex hormone exposure – and low facial fluctuating asymmetry – a marker of developmental stability – are associated with specific personality traits in both sexes. Recently, the interest in the dark triad of personality (Machiavellianism, narcissism, and psychopathy) has increased. However, whether 2D:4D and facial fluctuating asymmetry are related to and predictive to the dark triad remain unknown. The aim of this study was to fill this gap by assessing the relationship between these variables. A group of 119 healthy college students (71 females) answered the short dark triad questionnaire. Photographs were used to determine their degree of facial fluctuating asymmetry and the digit ratios (2D:4D) on both hands were directly measured. The data revealed that narcissism was predicted by lower left-hand 2D:4D and lower facial fluctuating asymmetry. We suggested that a trait related to variations in sex hormone levels (measured by lower 2D:4D) and to developmental stability (measured by lower facial fluctuating asymmetry) contributes to higher narcissistic tendencies in both sexes, which might serve as a reinforcement strategy that increases their attractiveness and is rewarded by increased social status and mating partners.