Background: The COVID-19 pandemic is still ongoing and is not yet under control. Evidence regarding the impacts of COVID-19 on psychological distress has been widely reported worldwide, and one of the primary concerns regarding psychological distress is fear (ie, fear of COVID-19). Therefore, having a robust instrument for assessing fear of COVID-19 is important. The present systematic review aimed to synthesize the psychometric evidence evaluated using item response theory (IRT) on the Fear of COVID-19 Scale (FCV-19S). Methods: Utilizing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, four academic databases (Scopus, PubMed Central, ProQuest, and ISI Web of Knowledge) were used to search target papers. Keywords used for search were "Fear of COVID-19 Scale" and its abbreviation (ie, "FCV-19S") and IRT-related terms. The COnsensus-based Standards for the selection of health status Measurement INstruments (COSMIN) checklist was then applied to evaluate the methodological quality of the reviewed papers. Moreover, psychometric properties using IRT methods were synthesized using a qualitative method. Results: The initial search resulted in 552 papers (73 duplicates) and 479 were screened based on their titles and abstracts. Finally, 16 papers were included for review regarding their methodological quality (via COSMIN) to synthesize the psychometric evidence for FCV-19S. The 16 papers included 21 countries with 16 language versions of FCV-19S. Conclusion: All the psychometric evidence indicated that the seven items in the FCV-19S fit with the concept of fear. The FCV-19S is a strong and valid instrument for assessing fear across different languages. The seven items in the FCV-19S appear to be unidimensional in assessing fear, which indicates that all items are necessary in the FCV-19S.