Introduction: Animal-Assisted Interventions (AAIs) have been increasingly used in the workplace to mitigate the effect of work-related stress and improve psychological well-being among employees. Military workers returning home from combat and veterans face a high burden of post-traumatic stress disorders (PTSD). This systematic review aimed to investigate the potential benefits of AAIs on military workers and veterans affected by PTSD. Methods: A systematic review was conducted across Scopus, PubMed Central/Medline, Web of Science, and Google Scholar in December 2021 and June 2022 using predefined search criteria. All types of studies published in the English language were included except editorials, commentaries, and narrative reviews. Studied published from January 2001 to December 2021 were included. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 reporting guidelines for this systematic review. The assessment of study quality was carried out with a 16-item Quality Assessment Tool for Studies with Diverse Designs (QATSDD) Results: Overall, 25 studies were finally included in this systematic review. Most of the AAIs were canine-assisted programs (n=12) and therapeutic horseback riding or equine-assisted psychotherapy (n=11). There was only one intervention study utilizing a pinnipeds-based program (n=1), while one study was based on several types of animals (n=1). Out of 25 studies focusing on the effects of AAIs on PTSD in the military (n=3) and veterans (n=21), the majority of them (n=18) observed significantly lower PTSD symptomatology following AAIs. Three studies observed no statistically significant difference in PTSD symptomatology. Discussion: Our findings indicated that implementing AAI programs among military workers and veterans may improve their psychological well-being and reduce the severity of PTSD symptoms. Policymakers and occupational health services should consider adopting AAIs during military service and after military discharge to support the mental health of military workers.