Mental health impacts of COVID-19 pandemic have received a great deal of attention by policymakers for the management of present and future cases of the pandemic, especially as new COVID-19 variant cases are on the rise. Thus, this study seeks to conduct a systematic review to address the following research questions: (1) What are the mental health impacts of COVID-19 in the empirical literature? (2) Which categories of people are at higher risk of the mental health impacts of the pandemic based on the extant literature? A sample of 35 studies out of 196 potential studies (from various databases, including Scopus, Google Scholar, , Research Gate, PubMed, , and libraries, from 2020 to 2022) were used after a comprehensive literature search and thorough assessment based on PRISMA-P guidelines. The study reveals that the pandemic has led to severe cases of mental health challenges such as depression, anxiety, post-traumatic stress disorder, psychological disorders, mood disorders, and insomnia. The review identified groups such as health workers, patients with pre-existing psychiatric or mental health issues, COVID-19 survivors, patients with underlying health conditions, and the elderly as the most vulnerable groups to mental health challenges from the pandemic.