Adverse childhood experiences (ACEs) comprise many dimensions of abuse and neglect in early development. Attention deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder that often begins in childhood. In this review, we investigated the associations between ACEs and ADHD in children. Specifically, the focus is to determine the extent of the relationship between ACE type, cumulative number, and ADHD severity. Furthermore, this study explored all aspects of the bidirectional nature of this relationship including how children with ADHD may experience greater ACEs and the potential contribution of confounding and mediating variables including comorbid conditions and resilience. Selected studies were published between January 2015 and January 2023 on PsychInfo, Google Scholar, PubMed, and Scopus. Selected studies included: (1) The main age group of the study was children; (2)The children had to have been diagnosed with or have parent-reported ADHD; and (3)The research must include ACE. Case studies and those not meeting the inclusion criteria were excluded from this review. Ultimately, 43 studies met the inclusion criteria, were included in this review, and were evaluated using the appropriate risk of bias assessment tools. These studies supported a positive association between ACEs and ADHD including cumulative quantity and select types of ACEs increasing ADHD severity. Previous literature has primarily utilized observational methodologies which prevent researchers from establishing if there are causal associations and if there is a temporal order to ACEs and ADHD development. This review also provides implications for future research.