Hashimoto's encephalopathy (HE) may often present initially with psychiatric symptoms. These presentations are often variable in clinical aspects, and there has been no systematic analysis of the numerous psychiatric presentations heralding an eventual diagnosis of HE which will guide clinicians to make a correct diagnosis of HE. This systematic review was done to analyze the demographic characteristics, symptom typology, and clinical and treatment variables associated with such forerunner presentations. Electronic databases such as PubMed, ScienceDirect, and Google Scholar databases were searched to identify potential case reports that described initial psychiatric presentations of HE in English language peer-reviewed journals. The generated articles were evaluated and relevant data were extracted using a structured tool. We identified a total of forty articles that described 46 cases. More than half of the total samples (54.4%) were above the age of 50 years at presentation. The most common psychiatric diagnosis heralding HE was acute psychosis (26.1%) followed by depressive disorders (23.9%). Dementia (10.9%) and schizophrenia (2.2%) were uncommon presentations. Antithyroid peroxidase antibodies were elevated in all patients but not antithyroglobulin antibodies. Preexisting hypothyroidism was absent in majority of cases (60.9%). Steroid doses initiated were 500-1000 mg of intravenous methylprednisolone for majority (52.1%) of patients while oral steroid maintenance was required for a significant minority (39.1%). Psychiatric manifestations of HE may be heterogeneous and require a high index of clinical suspicion, especially in older adults. A range of clinical and treatment variables may assist clinicians in making a faster diagnosis and instituting prompt and effective management.