Background: The postpartum period can be emotionally challenging for parents, with documented levels of anxiety, stress, and depression. While the benefits of skin-to-skin contact (SSC) are well-known, its impact on the mental health of parents of full-term newborns has been less studied. Objective: We aimed to assess the effects of SSC in mental health outcomes in the parents of full-term newborns. Methods: In this systematic review, a comprehensive search was conducted to identify randomized clinical trials (RCTs) comparing SSC versus no SSC and assessing mental health outcomes. Meta-analyses were performed whenever possible, and the GRADE approach was used to rate the certainty of evidence. Results: We included 9 RCTs with 1201 participants. Regarding the risk of bias, the most affected domains were selective reporting, blinding, and allocation concealment. Regarding parental anxiety, SSC may reduce it at short-term, while it is unsure its effect at mid-term and it may not have any effect at long-term. Regarding Psychological stress, SSC may not have an impact at mid- and long-term. Regarding delivery-related post-traumatic stress symptoms, SSC may not have an impact at short-, mid-, and long-term. Regarding depressive symptoms, the evidence is uncertain at short- and mid-term. Limitations: For the assessed outcomes, certainty of the evidence was low or very low. Conclusion: SSC may reduce parental anxiety at short-term, while it may not have an impact in psychological stress and delivery-related post-traumatic stress symptoms. Moreover, the evidence is uncertain regarding its effect in long-term anxiety and depressive symptoms.