This research paper examined the influence of the COVID-19 pandemic on the GCC stock markets indices. By employing the Event Study Methodology (ESM), the findings confirmed that all GCC stock market indices were affected negatively by the COVID-19 pandemic. The GCC stock markets interacted negatively with the early announcement of the first confirmed cases of COVID-19 in Wuhan city in China in December 2019. They were greatly affected when the World Health Organization (WHO) announced that the COVID-19 virus had become a pandemic. The cumulative average abnormal returns (CAAR) for all of the GCC stock market indices revealed that all of the GCC stock markets were negatively affected by the COVID-19 pandemic during all investigated event windows.