Emotional dysregulation (ED) has recently been conceptualized as a transnosographic entity in major mental disorders, and increasing evidence has suggested association between ED and post-traumatic stress symptoms (PTSS), though the nature of this association is unclear. The aim of the present review was to examine the possible interplay between ED and trauma exposure in the literature, as well as a possible role for the comorbidity of PTSD or PTSS in adolescents and young adults. In particular, we explored whether ED may represent a risk factor for PTSD or, conversely, a consequence of traumatic exposure. This systematic review was conducted according to PRISMA 2020 guidelines in three databases (PubMed, Scopus, and Embase). The 34 studies included showed a wide heterogeneity in terms of the populations selected and outcomes examined. Most studies used the Difficulties in Emotion Regulation Scale (DERS) and examined the relationship between ED, trauma, and psychopathological manifestations after the occurrence of trauma, with a focus on child abuse. Although current data in the literature are heterogeneous and inconclusive, this research highlights the role of ED as a mechanism that may mediate vulnerability to PTSD, but also as a predictor of severity and maintenance of typical, atypical, or associated PTSD symptoms, suggesting prevention programs for PTSD and other mental disorders should support the development of emotion regulation strategies.