Because emotional exchanges are central in couple interactions, individual competences to manage one’s own emotions and those of others are important to develop a good relational intimacy with a romantic partner over time. It is assumed that individual differences in attachment orientation influence the development of emotional competences and intimacy between romantic partners. While emotional competences are important for the proper functioning of romantic relationships, little is known about their mediating role in the relationship between individual’s attachment orientation and relational intimacy. In five hundred and sixty-four heterosexual subjects, the present study aimed to assess the indirect effects of emotional competences (both intrapersonal and interpersonal) on the relationship between insecure attachment orientations (both avoiding and anxious dimensions) and relational intimacy (i.e., engagement, communication and shared friends dimensions). Direct effects between our variables of interest were also explored. The results highlighted a negative association between both insecure avoiding and anxious attachment orientations and intrapersonal emotional competences. However, only the avoiding orientation was negatively related to interpersonal emotional competences. Furthermore, the anxious attachment dimension was negatively related to a feeling of engagement, in contrast to the avoiding attachment dimension that was associated with a low level of engagement, positive communication, and shared friends. Multi-group analysis highlighted gender invariance in the model. The findings suggest that although insecure attachment has a negative effect on the couple relationship, the capacity to manage one’s own emotions appears to be a protective factor for relational intimacy regarding its mediating role in these associations.