The crucial role of Nachträglichkeit/après-coup (N/AC) in psychoanalytic psychology has been afforded lower consideration in the scientific literature than other relevant psychoanalytic constructs. No systematic reviews have been provided on this construct. We aimed at investigating the many facets of the psychoanalytic significance N/AC as addressed in the scientific literature, outlining its potential developments. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we selected peer-reviewed, indexed articles based on the psychoanalytic concept of N/AC in the scientific literature. The keywords we entered in Pubmed, Web of Science, Scopus, and Psychoanalytic Electronic Publishing (PEP) were: Nachträglichkeit, après-coup, and psych*. Studies published between the 1950s and 2022 were considered. The initial database search yielded 600 results. After duplicates removal, 414 contributions were screened, of which 35 articles met the inclusion criteria. A metasynthesis of the latter revealed that N/AC is crucially involved in four different—albeit partially overlapping—domains, where N/AC respectively features as (a) a metapsychological construct explicative of the retroactive constitution of experience, (b) a cornerstone for the emergence of traumatic psychopathology, (c) a resource of the therapeutic process in clinical settings, and (d) a core facet of meaning-making processes involved in the constitution of memory. As a nonlinear, multidimensional process, N/AC is still recognized as a crucial concept in the scientific literature. Yet, no attempts were found, which investigated the phenomenon from an empirical standpoint. Based on the theoretical cues provided in the selected literature, future explorations of N/AC in terms of meaning-making processes and neuroscientific perspectives are suggested.